Triangle Practice Problems & Worksheets - Free Online

Master triangle types, angles, area, perimeter, and congruence with step-by-step practice problems. Perfect for students learning geometry fundamentals.

📚Master Triangle Concepts with Interactive Practice
  • Identify equilateral, isosceles, right, and scalene triangles by their properties
  • Calculate missing angles using the 180-degree angle sum rule
  • Find triangle area using base × height ÷ 2 formula
  • Determine triangle perimeter by adding all three side lengths
  • Apply congruence theorems (SSS, SAS, ASA, SSA) to prove triangles equal
  • Use similarity principles to solve proportional triangle problems

Understanding Triangle

Complete explanation with examples

Triangle

In this article, we will briefly learn everything necessary about triangles and also practice with some exercises!
Let's get started!

Detailed explanation

Practice Triangle

Test your knowledge with 38 quizzes

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

444777AAABBBCCC8.06

Examples with solutions for Triangle

Step-by-step solutions included
Exercise #1

Calculate the area of the right triangle below:

101010666888AAACCCBBB

Step-by-Step Solution

Due to the fact that AB is perpendicular to BC and forms a 90-degree angle,

it can be argued that AB is the height of the triangle.

Hence we can calculate the area as follows:

AB×BC2=8×62=482=24 \frac{AB\times BC}{2}=\frac{8\times6}{2}=\frac{48}{2}=24

Answer:

24 cm²

Video Solution
Exercise #2

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

121212888999AAABBBCCCDDD

Step-by-Step Solution

First, let's remember the formula for the area of a triangle:

(the side * the height that descends to the side) /2

 

In the question, we have three pieces of data, but one of them is redundant!

We only have one height, the line that forms a 90-degree angle - AD,

The side to which the height descends is CB,

Therefore, we can use them in our calculation:

CB×AD2 \frac{CB\times AD}{2}

8×92=722=36 \frac{8\times9}{2}=\frac{72}{2}=36

Answer:

36 cm²

Video Solution
Exercise #3

What is the area of the triangle in the drawing?

5557778.68.68.6

Step-by-Step Solution

First, we will identify the data points we need to be able to find the area of the triangle.

the formula for the area of the triangle: height*opposite side / 2

Since it is a right triangle, we know that the straight sides are actually also the heights between each other, that is, the side that measures 5 and the side that measures 7.

We multiply the legs and divide by 2

5×72=352=17.5 \frac{5\times7}{2}=\frac{35}{2}=17.5

Answer:

17.5

Video Solution
Exercise #4

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 #5

Calculate the area of the following triangle:

666777AAABBBCCCEEE

Step-by-Step Solution

The formula for the area of a triangle is

A=hbase2 A = \frac{h\cdot base}{2}

Let's insert the available data into the formula:

(7*6)/2 =

42/2 =

21

Answer:

21

Video Solution

Frequently Asked Questions

What are the 4 main types of triangles and their properties?

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The four main types are: 1) Equilateral - all sides and angles equal (60° each), 2) Isosceles - two equal sides and two equal base angles, 3) Right - one 90° angle with two legs and hypotenuse, 4) Scalene - all sides different lengths.

How do you find the area of a triangle step by step?

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Use the formula: Area = (base × height) ÷ 2. First identify the base (any side) and corresponding height (perpendicular distance from opposite vertex to base). For right triangles, multiply the two legs and divide by 2.

Why do triangle angles always add up to 180 degrees?

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This is a fundamental geometric property. In any triangle, the three interior angles must sum to exactly 180°. This rule helps you find missing angles when you know the other two angles.

What is the difference between congruent and similar triangles?

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Congruent triangles have identical angles AND side lengths - they're exactly the same size. Similar triangles have the same angles but proportional sides - they're the same shape but different sizes.

How do you calculate triangle perimeter for different triangle types?

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Perimeter equals the sum of all three sides: • Equilateral: 3 × side length • Isosceles: 2 × equal side + base • Right triangle: leg₁ + leg₂ + hypotenuse • Scalene: side₁ + side₂ + side₃

What are the triangle congruence theorems I need to know?

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The main congruence theorems are: SSS (three sides equal), SAS (two sides and included angle), ASA (two angles and included side), and SSA (two sides and angle opposite larger side). These prove triangles are identical.

How do you identify if a triangle is right angled?

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A right triangle has exactly one 90° angle. You can identify it by: checking if one angle equals 90°, using the Pythagorean theorem (a² + b² = c²), or looking for the characteristic leg-hypotenuse relationship.

What is the special 45-45-90 triangle and its properties?

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This is a right triangle with two 45° angles, making it both right and isosceles. The sides are in the ratio 1:1:√2, where the legs are equal and the hypotenuse is √2 times longer than each leg.

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