IXL | Triangle Angle-Sum Theorem

The diagram shows a triangle.

30°

What is the value of

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Learn with an example

The diagram shows a triangle.

69°

55°

What is the value of

The sum of the interior angle measures of a triangle is 180°.

First, look at the interior angle measures in the triangle.

Set the sum of the interior angle measures of the triangle equal to 180°. Solve for

69°

55°

180°

124°

Combine like terms

180°

Combine like terms

Subtract 124° from both sides

56°

Subtract 124° from both sides

Divide both sides by 2

28°

Divide both sides by 2

So,

28°

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