IXL | Find missing angles in quadrilaterals II

A parallelogram has one angle that measures 10°. What are the measures of the other three angles in the parallelogram?

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question

A parallelogram has one angle that measures 85°. What are the measures of the other three angles in the parallelogram?

°, °, and °

key idea

Opposite angles of a parallelogram are congruent.

The measures of the angles of a parallelogram add up to 360°.

solution

One of the missing angles is opposite the 85° angle. Since opposite angles are congruent, this missing angle is 85°.

Find the other two missing angles. Set the sum of the angle measures equal to 360° and solve.

85° + 85° + n + n

360°

Add

170° + 2n

360°

Add

Subtract 170° from both sides

360° − 170°

Subtract 170° from both sides

Simplify

190°

Simplify

Divide both sides by 2

95°

Divide both sides by 2

Two of the missing angles are 95°.

So, the missing angles are 85°, 95°, and 95°.

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Not feeling ready yet? These can help:

Z.10Find missing angles in quadrilaterals I

Z.5Classify quadrilaterals I

T.14Solve equations involving like terms

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