Geometry and TrigonometryEasy–MediumValue of x from a pair of vertical angles
Geometry and Trigonometry practice question
Two straight lines cross. One of the pairs of vertical angles they form measures (3x + 10)° and (5x − 30)°. What is the value of x?
Answer: 20
Vertical angles are equal: 3x + 10 = 5x − 30, so 2x = 40 and x = 20.
Common wrong answers
- If you answered 10
- 10 solves 3x + 10 = 5x − 10.
- If you answered 25
- 25 sets the two angles' sum to 180, treating them as a linear pair.
- If you answered 70
- 70 is the measure of each angle, not x.
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- Easy–Medium
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