IXL | Find missing angles in triangles

The diagram shows a triangle.

106°

43°

What is the value of

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Learn with an example

question

The diagram shows a triangle.

109°

30°

What is the value of

key idea

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

solution

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

109

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

109°

30°

180°

139°

Combine like terms

180°

Combine like terms

Subtract 139° from both sides

41°

Subtract 139° from both sides

So,

41°

Looking for more? Try these:

Lesson: Interior angles of triangles

Lesson: Types of triangles

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Teacher tools

Work it out

Not feeling ready yet? These can help:

EE.10Sums of angles in polygons

Q.2Classify triangles

Lesson: Interior angles of triangles

Lesson: Types of triangles

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