Just need on this pre-calc math problem in webassign (homework), only need with a), then i'll learn how to do the rest

Step-by-step explanation:

Positive angles are measured counterclockwise from 0.  Negative angles are measured clockwise from 0.  So cos(-π/6) = √3/2.

Or, you can use angle reflection properties.

cos(-x) = cos x

cos(-π/6) = cos(π/6) = √3/2

Another way to look at it is to add 2π to the angle to turn it into a positive angle.

cos(-π/6) = cos(11π/6) = √3/2

50

Step-by-step explanation:

AE= 40

90° degree angle

90+40= 130

half circle so 180

180-130=50