Question

if cos A=4/5 then find sin A​

Answer 1

Answer: We know that : $sin^(2)x+ cos^(2)x = 1$

as a trigonometric identity.

Then cos A=4/5

sin^2(A)= 1- cos^2(A)

=1-(16/25)

25-16/25

9/25

Hence sin A = 3/5 (sin A is also equal to -3/5 since cos A given value lies in first or 4th quadrant )

So sin A can lie in 1st or 2nd or 3rd or 4th quadrant for

sin A= +3/5,-3/5.

Hope, it helps.

Step-by-step explanation: