16Hit1600
Geometry and TrigonometryMediumCorresponding angles with expressions

Geometry and Trigonometry practice question

In a figure, lines p and q are parallel and are crossed by a third line. Angle 1 and angle 5 are corresponding angles. If angle 1 measures (x + 20)° and angle 5 measures (2x − 40)°, what is the value of x?

Answer: 60

Corresponding angles between parallel lines are equal: x + 20 = 2x − 40. Subtract x: 20 = x − 40, so x = 60. Both angles measure 80°.

Common wrong answers

If you answered 20
20 comes from x = 60 − 40 with a slip; 20 + 40 = 60.
If you answered 80
80 is the measure of each angle in degrees, not x.
If you answered 66.67
66.67 (200/3) comes from setting the sum to 180. Corresponding angles are EQUAL, not supplementary.

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