Calculate X in an Equilateral Triangle: Finding the Value of 8X

Triangle Angles with Variable Expressions

ABC is an equilateral triangle.8X8X8XAAABBBCCCCalculate X.

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Step-by-step video solution

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00:00 Determine the value of X
00:03 In an equilateral triangle, all angles equal 60
00:07 Let's isolate X
00:13 This is the solution

Step-by-step written solution

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1

Understand the problem

ABC is an equilateral triangle.8X8X8XAAABBBCCCCalculate X.

2

Step-by-step solution

Since this is an equilateral triangle, all angles are also equal.

As the sum of angles in a triangle is 180 degrees, each angle is equal to 60 degrees. (180:3=60)

From this, we can conclude that: 60=8x 60=8x

Let's divide both sides by 8:

608=8x8 \frac{60}{8}=\frac{8x}{8}

7.5=x 7.5=x

3

Final Answer

7.5

Key Points to Remember

Essential concepts to master this topic
  • Angle Sum: All triangles have interior angles totaling 180°
  • Equilateral Property: All angles equal 60° since 180°÷3=60° 180° ÷ 3 = 60°
  • Check: Substitute x = 7.5 into 8x: 8(7.5) = 60° ✓

Common Mistakes

Avoid these frequent errors
  • Forgetting equilateral triangles have equal angles
    Don't assume you need more information or create complex equations! This leads to unnecessary steps and confusion. Always remember equilateral triangles have three 60° angles, so set your expression equal to 60°.

Practice Quiz

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

FAQ

Everything you need to know about this question

Why are all angles in an equilateral triangle 60°?

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Since an equilateral triangle has all sides equal, all angles must also be equal. The sum of angles in any triangle is 180°, so each angle is 180°3=60° \frac{180°}{3} = 60° .

What if the triangle wasn't equilateral?

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If it were isosceles (two equal sides), you'd have two equal angles. If it were scalene (all different sides), you'd need more information to solve for x.

How do I know which angle equals 8x?

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It doesn't matter which specific angle equals 8x! Since all angles are equal in an equilateral triangle, any angle can be set equal to 60°.

Can I solve this without knowing it's equilateral?

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No! The key information is that ABC is equilateral. Without this, you can't determine that each angle equals 60°, making the problem unsolvable.

What if I get a different value for x?

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Double-check your setup: 8x=60° 8x = 60° , so x=608=7.5 x = \frac{60}{8} = 7.5 . If you used 180° instead of 60°, you'd get the wrong answer!

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