Equilateral Triangle Practice Problems - Interactive Exercises

Master equilateral triangle concepts with step-by-step practice problems. Learn to calculate angles, perimeter, area, and identify properties of regular triangles.

📚Practice Equilateral Triangle Problems and Build Your Geometry Skills
  • Calculate angles in equilateral triangles knowing each measures exactly 60 degrees
  • Find perimeter by multiplying side length by 3 using the equal sides property
  • Determine unknown side lengths when given the perimeter of regular triangles
  • Solve complex area problems involving equilateral triangles and semicircles
  • Identify characteristics of regular three-sided polygons and their remarkable points
  • Apply Pythagorean theorem to find heights in equilateral triangle problems

Understanding Equilateral triangle

Complete explanation with examples

Definition of equilateral triangle

The equilateral triangle is a triangle that all its sides have the same length.

This also implies that all its angles are equal, that is, each angle measures 60° 60° degrees (remember that the sum of the angles of a triangle is 180° 180° degrees and, therefore, these 180° 180° degrees are divided equally by the three angles).

Detailed explanation

Practice Equilateral triangle

Test your knowledge with 20 quizzes

Does the diagram show an obtuse triangle?

Examples with solutions for Equilateral triangle

Step-by-step solutions included
Exercise #1

In a right triangle, the side opposite the right angle is called....?

Step-by-Step Solution

The problem requires us to identify the side of a right triangle that is opposite to its right angle.
In right triangles, one of the most crucial elements to recognize is the presence of a right angle (90 degrees).
The side that is directly across or opposite the right angle is known as the hypotenuse. It is also the longest side of a right triangle.
Therefore, when asked for the side opposite the right angle in a right triangle, the correct term is the hypotenuse.

Selection from the given choices corroborates our analysis:

  • Choice 1: Leg - In the context of right triangles, the "legs" are the two sides that form the right angle, not the side opposite to it.
  • Choice 2: Hypotenuse - This is the correct identification for the side opposite the right angle.

Therefore, the correct answer is Hypotenuse \text{Hypotenuse} .

Answer:

Hypotenuse

Exercise #2

In an isosceles triangle, what are each of the two equal sides called ?

Step-by-Step Solution

In an isosceles triangle, there are three sides: two sides of equal length and one distinct side. Our task is to identify what the equal sides are called.

To address this, let's review the basic properties of an isosceles triangle:

  • An isosceles triangle is defined as a triangle with at least two sides of equal length.
  • The side that is different in length from the other two is usually called the "base" of the triangle.
  • The two equal sides of an isosceles triangle are referred to as the "legs."

Therefore, each of the two equal sides in an isosceles triangle is called a "leg."

In our problem, we confirm that the correct terminology for these two equal sides is indeed "legs," distinguishing them from the "base," which is the unequal side. This aligns with both the typical definitions and properties of an isosceles triangle.

Thus, the equal sides in an isosceles triangle are known as legs.

Answer:

Legs

Exercise #3

In a right triangle, the two sides that form a right angle are called...?

Step-by-Step Solution

In a right triangle, there are specific terms for the sides. The two sides that form the right angle are referred to as the legs of the triangle. To differentiate, the side opposite the right angle is called the hypotenuse, which is distinct due to being the longest side. Hence, in response to the problem, the sides forming the right angle are correctly identified as Legs.

Answer:

Legs

Exercise #4

Does the diagram show an obtuse triangle?

Step-by-Step Solution

To determine if the triangle in the diagram is obtuse, we will visually assess the angles:

  • Step 1: Identify the angles in the diagram. The triangle has three angles, with one angle appearing between the horizontal base and the left slanted side.
  • Step 2: Evaluate the angle between the base and the left side. If it opens wider than a right angle, it's considered obtuse. This angle seems to be greater than 9090^\circ, indicating obtuseness.
  • Step 3: Conclude based on visual inspection. Since this key angle is greater than 9090^\circ, the triangle must be an obtuse triangle.

Therefore, the solution to the problem is Yes; the diagram does show an obtuse triangle.

Answer:

Yes

Video Solution
Exercise #5

Does the diagram show an obtuse triangle?

Step-by-Step Solution

To determine if the triangle shown in the diagram is obtuse, we proceed as follows:

  • Step 1: Identify that the diagram is indeed a triangle by observing the confluence of three edges forming a closed shape.
  • Step 2: Appreciate the geometric arrangement of the triangle, focusing on the sides' lengths and angles visually.
  • Step 3: Noticeably, the longest side of the triangle represents a noticeable tilt indicating the presence of an obtuse angle.

Based on the observation above, notably from the triangle's longest side against the base, it's clear that one angle is larger than 9090^\circ. Hence, the triangle in the diagram is indeed an obtuse triangle.

Therefore, the correct answer is Yes.

Answer:

Yes

Video Solution

Frequently Asked Questions

What makes a triangle equilateral and how do I identify one?

+
An equilateral triangle has all three sides of equal length and all three interior angles measuring exactly 60 degrees. It's also called a regular three-sided polygon because both sides and angles are equal.

How do I calculate the perimeter of an equilateral triangle?

+
Since all sides are equal, multiply the length of one side by 3. For example, if one side is 5 cm, the perimeter is 3 × 5 = 15 cm.

What are the angle measures in an equilateral triangle?

+
All three interior angles in an equilateral triangle measure 60 degrees each. Since triangle angles sum to 180°, each angle gets 180° ÷ 3 = 60°.

How do I find a missing side length if I know the perimeter?

+
Divide the total perimeter by 3. For instance, if the perimeter is 33 cm, each side length is 33 ÷ 3 = 11 cm.

What special properties do equilateral triangles have?

+
Key properties include: 1) All remarkable lines (heights, medians, bisectors) coincide, 2) All remarkable points meet at the same center point, 3) It's classified as an acute triangle since all angles are less than 90°.

How do I calculate the area of an equilateral triangle?

+
Use the formula: Area = (side² × √3) ÷ 4. First find the height using the Pythagorean theorem, then apply the standard triangle area formula: (base × height) ÷ 2.

What's the difference between equilateral, isosceles, and scalene triangles?

+
Equilateral triangles have all three sides equal, isosceles triangles have exactly two equal sides, and scalene triangles have no equal sides. This classification is based on side lengths.

Why is an equilateral triangle called a regular polygon?

+
A regular polygon has all sides equal and all angles equal. Since equilateral triangles meet both criteria with three equal sides and three 60° angles, they qualify as regular three-sided polygons.

More Equilateral triangle Questions

Continue Your Math Journey

Practice by Question Type