Practice questions
- Find angle b:
A. 120 degrees B. 125 degrees C. 104 degrees D. 130 degrees
- Angle b is a(n)
A. acute angle. B. straight angle. C. obtuse angle. D. reflex angle.
Answers and explanations
- The correct answer is Choice (D).
Angles around a point always add up to 360 degrees. The diagram shows the measurements of all the angles except b, so you can solve this problem in a couple of ways. You can use algebra:
You can also subtract the angles you know from 360 to find what's left over, which is b:
360 – 68 – 80 – 82 = 130
- The correct answer is Choice (D).
A reflex angle is one that's greater than 180 degrees. An acute angle is one that's less than 90 degrees, a straight angle is a straight line that measures exactly 180 degrees, and an obtuse angle is one that's greater than 90 degrees but less than 180 degrees.