Question

If sin c= 3/4 then cos A=​

Answer 1

Step-by-step explanation:

Given, sinc= 3/4

⇒DC/BC = 3/4

⇒BC=3k and AC=4k

where k is the constant of proportionality.

By Pythagoras theorem, we have

AB^2 =AC ^2−BC ^2

=(4k)^2−(3k) ^2

=7k ^2

⇒AB= ✓7k

So, cosA= AB/AC

cosA= ✓7k/4k

=✓7/4