Triangle Area Using Trigonometry Practice Problems

Master calculating triangle area with trigonometry formulas through step-by-step practice problems. Perfect for geometry students learning sin, cos, tan applications.

📚Master Triangle Area Calculations with Trigonometry
  • Apply the formula Area = (1/2)ab sin(C) to find triangle areas
  • Calculate areas using two sides and included angle measurements
  • Work with degrees and radians in trigonometric area calculations
  • Solve real-world problems involving triangle area using trigonometry
  • Practice with right triangles, isosceles triangles, and scalene triangles
  • Convert between different angle measurements for accurate calculations

Understanding Area of a Triangle

Complete explanation with examples

How to calculate the area of a triangle using trigonometry?

Throughout geometry studies, which deal with various structures and shapes, you are required to calculate areas and perimeters. Each shape or structure has a different formula through which you can answer the question and calculate the area. Fortunately, there is one formula that can be applied to all triangles, and it can be used to calculate the area of a triangle using trigonometry.

In the field of mathematics, emphasis is also placed on trigonometry, which deals with the study of triangles, their angles, and sides. Every student is required to demonstrate knowledge of triangles (from right triangles to isosceles triangles), and thus also answer the question of how to calculate the area of a triangle using trigonometry.

One formula for all different triangles

Now that you know the formula for calculating the area of a triangle using trigonometry, you can use it in any question where you need to calculate areas in triangles. The formula for calculating the triangle:

Diagram of a triangle labeled ABC with sides AB = 5, AC = 8, and angle Y = 60°. The area formula  𝑆 𝐴𝐵𝐶 = (𝐴𝐵⋅𝐴𝐶⋅sin𝛾)/2 is shown.

Detailed explanation

Practice Area of a Triangle

Test your knowledge with 27 quizzes

Calculate the area of the triangle below, if possible.

8.68.68.6777555

Examples with solutions for Area of a Triangle

Step-by-step solutions included
Exercise #1

Complete the sentence:

To find the area of a right triangle, one must multiply ________________ by each other and divide by 2.

Step-by-Step Solution

To solve this problem, begin by identifying the elements involved in calculating the area of a right triangle. In a right triangle, the two sides that form the right angle are known as the legs. These legs act as the base and height of the triangle.

The formula for the area of a triangle is given by:

A=12×base×height A = \frac{1}{2} \times \text{base} \times \text{height}

In the case of a right triangle, the base and height are the two legs. Therefore, the process of finding the area involves multiplying the lengths of the two legs together and then dividing the product by 2.

Based on this analysis, the correct way to complete the sentence in the problem is:

To find the area of a right triangle, one must multiply the two legs by each other and divide by 2.

Answer:

the two legs

Exercise #2

Calculate the area of the following triangle:

444555AAABBBCCCEEE

Step-by-Step Solution

The formula for calculating the area of a triangle is:

(the side * the height from the side down to the base) /2

That is:

BC×AE2 \frac{BC\times AE}{2}

We insert the existing data as shown below:

4×52=202=10 \frac{4\times5}{2}=\frac{20}{2}=10

Answer:

10

Video Solution
Exercise #3

Calculate the area of the triangle using the data in the figure below.

101010222AAABBBCCC

Step-by-Step Solution

To solve the problem of finding the area of triangle ABC \triangle ABC , we follow these steps:

  • Step 1: Identify the given measurements.
  • Step 2: Use the appropriate formula for the area of a triangle.
  • Step 3: Calculate the area using these measurements.

Let's go through each step in detail:
Step 1: From the figure, the base AB=10 AB = 10 and height AC=2 AC = 2 .
Step 2: The formula for the area of a triangle is: Area=12×base×height \text{Area} = \frac{1}{2} \times \text{base} \times \text{height} .
Step 3: Substituting the known values into the formula, we get:

Area=12×10×2=12×20=10 \text{Area} = \frac{1}{2} \times 10 \times 2 = \frac{1}{2} \times 20 = 10

Therefore, the area of triangle ABC \triangle ABC is 10.

Answer:

10

Video Solution
Exercise #4

Calculate the area of the triangle using the data in the figure below.

444777AAABBBCCC8.06

Step-by-Step Solution

To solve for the area of a triangle when the base and height are given, we'll use the formula:

Area=12×base×height \text{Area} = \frac{1}{2} \times \text{base} \times \text{height}

Given:

  • Base = 44 units

  • Height = 77 units

Apply the formula:

Area=12×4×7=12×28=14 \begin{aligned} \text{Area} &= \frac{1}{2} \times 4 \times 7 \\ &= \frac{1}{2} \times 28 \\ &= 14 \end{aligned}

Thus, the area of the triangle is 1414 square units.

Answer:

14

Video Solution
Exercise #5

Calculate the area of the following triangle:

4.54.54.5777AAABBBCCCEEE

Step-by-Step Solution

To find the area of the triangle, we will use the formula for the area of a triangle:

Area=12×base×height \text{Area} = \frac{1}{2} \times \text{base} \times \text{height}

From the problem:

  • The length of the base BC BC is given as 7 units.
  • The height from point A A perpendicular to the base BC BC is given as 4.5 units.

Substitute the given values into the area formula:

Area=12×7×4.5 \text{Area} = \frac{1}{2} \times 7 \times 4.5

Calculate the expression step-by-step:

Area=12×31.5 \text{Area} = \frac{1}{2} \times 31.5

Area=15.75 \text{Area} = 15.75

Therefore, the area of the triangle is 15.75 15.75 square units. This corresponds to the given choice: 15.75 15.75 .

Answer:

15.75

Video Solution

Frequently Asked Questions

What is the trigonometric formula for triangle area?

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The trigonometric formula for triangle area is Area = (1/2)ab sin(C), where 'a' and 'b' are two sides of the triangle and 'C' is the included angle between them. This formula works for all types of triangles.

How do you calculate triangle area when given two sides and an angle?

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To calculate triangle area with two sides and an angle: 1) Identify the two given sides (a and b), 2) Find the included angle (C) between these sides, 3) Apply the formula Area = (1/2)ab sin(C), 4) Calculate sin(C) using your calculator, 5) Multiply and divide by 2 for the final answer.

Why use trigonometry instead of base times height for triangle area?

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Trigonometry is used when you don't know the height of the triangle directly. The formula Area = (1/2)ab sin(C) allows you to find area using only two sides and the included angle, which is often more practical in real-world problems.

What angle should I use in the trigonometric area formula?

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Always use the included angle - the angle that lies between the two given sides. If you have sides AB and AC, use angle A (the angle at vertex A). Using the wrong angle will give an incorrect result.

Does the trigonometric area formula work for all triangle types?

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Yes, the formula Area = (1/2)ab sin(C) works for all triangles: right triangles, isosceles triangles, scalene triangles, acute triangles, and obtuse triangles. It's a universal formula for triangle area calculation.

How do I convert degrees to use in trigonometric calculations?

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Most calculators handle degrees directly - just ensure your calculator is in degree mode. If working with radians, multiply degrees by π/180. For example, 60° = 60 × π/180 = π/3 radians.

What if I get a negative result using the trigonometric area formula?

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Area cannot be negative. If you get a negative result, check that: 1) You're using the correct included angle, 2) Your calculator is in the right mode (degrees/radians), 3) You've identified the correct sides. The sine of any angle in a triangle is always positive.

Can I use this formula if I only know one side of the triangle?

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No, you need at least two sides and the included angle to use Area = (1/2)ab sin(C). If you only have one side, you'll need additional information like another side, another angle, or the triangle's height to calculate the area.

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