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

Is the triangle in the drawing a right triangle?

Examples with solutions for Equilateral 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 equilateral and how do I identify one?

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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?

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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?

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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?

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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?

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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?

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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?

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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?

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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.

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