If sinx = 0.3, and x is in Quadrant III, then what is the value of cosx?

Question

If sinx = 0.3, and x is in Quadrant III, then what is the value of cosx?

0

Answers ( No )

    0
    2021-09-08T22:04:31+00:00

    Probably the question should say \sin x=-0.3, as \sin x is negative for \pi<x<\dfrac{3\pi}2.

    In that case, recall that

    \cos^2x+\sin^2x=1\implies\cos x=\pm\sqrt{1-\sin^2x}

    Because x lies in the third quadrant, we expect \cos x to also be negative, so we take the negative root above. Then

    \cos x=-\sqrt{1-(-0.3)^2}\approx-0.954

    0
    2021-09-08T22:04:32+00:00

    SOS

    Answer:

    Use the trig identities: SOH CAH TOA

    • sin(x) = 0.3
    • cos(x) = √0.9

    Hope this helps!!!

    Sofia

Leave an answer

Browse
Browse