Carcass wrote:
In the circle above, with center O intersected by 2 straight lines, 3a = b. What is the value of b − a?
(A) 2
(B) 30
(C) 45
(D) 90
(E) 135
Given:
3a = bWe know that a + b = 180 degrees
Replace
b with
3a to get: a +
3a = 180
Simplify: 4a = 180
Solve: a = 45
Plug a = 45 into
3a = b to get: 3(45) = b
So, b = 135
So, b - a = 135 - 45 = 90
Answer: D
Aside: Notice that we can ignore the circle information and still solve this question.
_________________
Brent Hanneson - founder of Greenlight Test Prep