Question

In ΔABC shown below, use an appropriate trigonometric ratio to find m∠B. Round to the nearer degree.

A. 60
B. 53
C. 37
D. 30

Answer 1

cos b = adj/hyp
cos b = 4 / 5

Answer 2

SOH CAH TOA
nice trick also if you understand it

Answer 3

cos b = 80 degrees
but that is not one of your choices...
using pyth theorem the other side is 3 (special right triangle 3-4-5)

sin b = 3/5 = 60 degrees.

not sure why cos did not work...let me think on that (they should have both came out to the same degrees