Question

2] If sina=0.8 Find cos3a
Ansi​

Answer 1

Given:

Sin A = 0.8

Sin A = 8/10

Sin A = Perpendicular/ Hypotenuse. :Base=B, Perpendicular=P, Hypotenuse=H

P/H =8/10

P=8

H=10

H^2=Base^2+P^2 :Pythagoras Theorem

10^2=B^2+8^2

100=B^2+64

B=√(100-64)

B=√36

B=6

Cos A = Base/ Hypotenuse

Cos A = 6/10

Cos A = 3/5

Cos^3 A = (3/5)^3

Cos^3 A = 27/125.