Question

assume that angle A+angle B=180 degrees. which of the following is equal to cos B
A. Sin A
B. -Sin A
C. Cos B
D. - Cos B

Answer 1

pls EXPLAIN how u get the answer

Answer 2

Maybe I'm missing something... Isn't cosB equal to cosB?

Answer 3

The other possible answer is -cosA but that's not there

Answer 4

A+B=180
B = 180-A
put cos to both sides, giving us
cosB = cos(180-A) or
cosB = -cosA

Answer 5

oops sorry the question asked for Cos A

Answer 6

Well that's solved then :)

Answer 7

yes! thanks @RadEn :)

Answer 8

and thanks BluFoot!