Question

What is `cos( arcsin( 5 / 13) + arctan( - 4 / 3 ))`?

Answer 1

Find cos (x - y)

Explanation:

`sin x = (5/13) --> x = 22.62` deg

`tan y = -4/3 --> y = - 53.13`

cos z = cos( x - y) = cos x.cos y + sin x.sin y =

= (0.92)(0.60) + (0.38)(-0.80) = 0.248 --> z = 75.64 deg

Check: cos z = cos (x - y) = cos (22.62 + 53.15) = cos (75.75)
Calculator gives: cos (75.75) = 0.246 OK