Question

sin 0=4/5and 0 is not in first quadrant, find the value of cos 0​

Answer 1

Theory :-

sin²θ + cos²θ = 1, &

Solutions of x² = a are, x = ±a

Solution :-

Using the given formula

$( \frac{4}{5} ) ^{2} + \cos ^{2} (x) = 1$

$or \: \cos^{2} (x) = ( { \frac{3}{5}) }^{2}$

So, cos(x) = ±(3/5)

Since, x is not in first quadrant and sin(x) = (+ve)

This means x is in second quadrant as in second quadrant only, sin(x) is positive, (other than first quadrant)

So, in second quadrant, cos(x) = (-ve)

Hence, we get cos(x) = -(3/5)

Hope you liked my answer

Pls mark me as brainliest

Thanks.