Question

If cosx=0.4, then cos(π−x)=_____

Answer 1

Answer:

-2/5

Step-by-step explanation:

cos(x) = 2/5

cos(π - x) = cosπ.cos(x) + sinπ.sin(x)

= -2/5

Answer 2

First find basic angle ∝

∝ = $cos^{-1}$ (0.4)

= 66.4 °

So cos lies in Quadrants 1 and 4

Q1 : x = 66.4°

Q4 : x = 293.6°

So ( $\pi$ - x )

= \pi - 66.4 = -63.3°

= \pi - 293.6 = -290.6°

cos ( \pi - x ) = 0.45  and  0.35