16Hit1600
Geometry and TrigonometryEasy–MediumSame-side interior angles at parallel lines

Geometry and Trigonometry practice question

Two parallel lines are cut by a transversal. A pair of same-side interior angles measures 3x° and x°. What is the value of x?

Answer: 45

Same-side interior angles add to 180: 3x + x = 180, so x = 45.

Common wrong answers

If you answered 60
60 divides 180 by 3.
If you answered 90
90 assumes the angles are equal, as if they were alternate angles.
If you answered 135
135 is the larger angle, 3x.

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