i never knew how to solve SOH CAH TOA.
Explain how you get the answer to this
A)
cos 18°
B)
sin 18°
C)
cos (90° – (72° – a))
D)
sin (90° – (72° – a))
2 Answers

72 – a = x
sin(x) = cos(90 – x)
sin(72 – a) = cos(90 – (72 – a))
C

cos (90° – (72° – a))
Remember, the “co” prefix of trigonometry functions means “of the complimentary angle”.
“The complimentary angle” is the angle that adds up with the given angle to equal 90 degrees.