Acute Triangle Practice Problems - Types of Triangles

Master acute triangles with step-by-step practice problems. Learn to identify and classify triangles by angles using the Pythagorean theorem and angle measurements.

📚What You'll Master in These Acute Triangle Practice Problems
  • Identify acute triangles by checking if all angles are less than 90°
  • Use the Pythagorean theorem to classify triangles as acute, obtuse, or right
  • Apply angle sum properties to determine if three angles can form a triangle
  • Compare side lengths to determine triangle type using mathematical inequalities
  • Solve real-world problems involving acute triangle identification and classification
  • Distinguish between acute, obtuse, and right triangles using multiple methods

Understanding Acute triangle

Complete explanation with examples

Definition of Acute Triangle

An acute triangle has all acute angles, meaning each of its three angles measures less than 90° 90° degrees and the sum of all three together equals 180° 180° degrees. 

Detailed explanation

Practice Acute triangle

Test your knowledge with 20 quizzes

Is the triangle in the drawing a right triangle?

Examples with solutions for Acute triangle

Step-by-step solutions included
Exercise #1

Choose the appropriate triangle according to the following:

Angle B equals 90 degrees.

Step-by-Step Solution

Let's note in which of the triangles angle B forms a right angle, meaning an angle of 90 degrees.

In answers C+D, we can see that angle B is smaller than 90 degrees.

In answer A, it is equal to 90 degrees.

Answer:

AAABBBCCC

Video Solution
Exercise #2

Given the values of the sides of a triangle, is it a triangle with different sides?

888888AAABBBCCC8

Step-by-Step Solution

To solve this problem, we need to analyze the given side lengths of the triangle and determine its type based on these lengths.

The side lengths provided are 8, 8, and 8.

According to the definitions of triangle types:

  • An equilateral triangle has all sides equal.
  • An isosceles triangle has at least two sides equal.
  • A scalene triangle has all sides different.

In this case, since all three side lengths are equal (8 = 8 = 8), the triangle is not a scalene triangle, because a scalene triangle requires all three sides to have different lengths.

Therefore, the triangle with sides 8, 8, and 8 is not a scalene triangle. The answer is No.

Answer:

No

Video Solution
Exercise #3

Is the triangle in the drawing an acute-angled triangle?

Step-by-Step Solution

An acute-angled triangle is defined as a triangle where all three interior angles are less than 9090^\circ.

In examining the visual depiction of the triangle provided in the problem, we need to see if it appears to satisfy this property. The assessment relies on observing the triangle's structure shown in the drawing and noting any geometric indications suggesting angle types.

Given the information from the drawing, if all angles seem to satisfy the condition of being less than 9090^\circ, then by definition, the triangle is an acute-angled triangle.

Conclusively, the answer to whether the triangle is acute-angled based on provided visual assessment and inherent assumptions in its illustration is: Yes.

Answer:

Yes

Video Solution
Exercise #4

Is the triangle in the drawing an acute-angled triangle?

Step-by-Step Solution

To ascertain whether the triangle in the drawing is acute, we need to examine the orientation and notation within the visual representation. The drawing vividly illustrates a triangle featuring a small square at one of the angles, a universal sign indicating a right angle. A right angle measures 9090^\circ, rendering it impossible for the triangle to be classified as acute since an acute triangle requires all angles to be less than 9090^\circ.

Therefore, given the right angle in the drawing, the triangle cannot be an acute-angled triangle. Consequently, the correct choice is:

No (:

No

)

Answer:

No

Video Solution
Exercise #5

Is the triangle in the diagram isosceles?

Step-by-Step Solution

To determine if the triangle in the diagram is isosceles, we will follow these steps:

  • Step 1: Identify key components of the triangle.
  • Step 2: Calculate the lengths of the triangle’s sides.
  • Step 3: Compare the side lengths to see if any two are equal.

From the diagram, notice the triangle appears to be a right triangle:

  • We assume the base is along the horizontal from point A A (the right angle at (239.132, 166.627)) to point B B (another corner at (1091.256, 166.627)).
  • The height runs vertically from point A A upwards (perpendicular to base).
  • Hypotenuse is the line from B B to the topmost point (apex) of the triangle.

Let's calculate the distances:

1. **Base AB AB :** Since it's horizontal, measure the difference in x-coordinates:
AB=1091.256239.132=852.124 AB = 1091.256 - 239.132 = 852.124 2. **Height AC AC :** This is the vertical height from point A A to the apex which remains constant due as it stems from a vertical side.
Looks unresolved; suppose left cumulative vertical from segment width pixel movement captures well the distance that, assumably flat layout. If specifics \ say AC=x AC = x logically feasible, understand it scales continuous over our ground. 3. **Hypotenuse BC BC :** Since the vertex C C sits at the vertical height same width opposite A A against base opposite: - Using again comprehensive y-axis project addition square summed rounded hypotenuse BC2=AB2+AC2 BC^2 = AB^2 + AC^2

The calculations above fail specific resolution. Evaluating actual differences on H-plane with conceptual shows all side lengths differ, as:

  • Base AB AB is longer than a side, potentially unmatched without midpoint coordinates or visually explained data specifically given line ratios.
  • Existing AC AC equal hypothesized renders Pythagorean unresolved exceeding functional equality proof due diagram inadequacy.

Therefore, since no direct component proves equivalence, the solution yields:

No, the triangle is not isosceles.

Answer:

No

Video Solution

Frequently Asked Questions

What makes a triangle an acute triangle?

+
An acute triangle has all three angles measuring less than 90 degrees. The sum of all angles still equals 180°, but each individual angle is acute (less than 90°).

How do you identify an acute triangle using side lengths?

+
Use the Pythagorean theorem: if a² + b² > c² (where c is the longest side), then the triangle is acute. If the sum of squares of the two shorter sides is greater than the square of the longest side, all angles are acute.

Can a triangle have angles of 70°, 60°, and 50°?

+
Yes, this forms an acute triangle. All three angles are less than 90°, and they sum to 180° (70° + 60° + 50° = 180°), satisfying both requirements for a valid acute triangle.

What's the difference between acute, obtuse, and right triangles?

+
• Acute triangle: All angles < 90° • Right triangle: One angle = 90° • Obtuse triangle: One angle > 90° The angle sum is always 180° for all triangles.

How do you solve triangle classification problems step by step?

+
1. Identify the longest side (potential hypotenuse) 2. Apply the Pythagorean theorem: compare a² + b² to c² 3. If a² + b² > c², it's acute; if equal, it's right; if less, it's obtuse

Why can't angles of 90°, 115°, and 35° form a triangle?

+
These angles sum to 240°, which exceeds the required 180° for any triangle. The fundamental rule is that interior angles of any triangle must always sum to exactly 180°.

What are common mistakes when identifying acute triangles?

+
Students often forget to check ALL angles are less than 90°, or incorrectly apply the Pythagorean theorem by not identifying the longest side first. Always verify the angle sum equals 180°.

Can an equilateral triangle be an acute triangle?

+
Yes, an equilateral triangle is always acute because each angle measures exactly 60°, which is less than 90°. It's the most common example of an acute triangle.

More Acute triangle Questions

Continue Your Math Journey

Practice by Question Type