Question

given sin (a)=(-43/45) and tan (a) > 0, determine the value of cos (a)

Answer 1

sin(a) is -ve and tan(a) is +ve
so (a) is in the 3rd Quad.

\[\sin^{-1}({43 \over 45}) = 72.85379\]

a = 180+72.85379 = 252.85379

Answer 2

you can also use the identity of

\[\sin^2 + \cos^2 =1\]

it will be a lot better

Answer 3

so whts the value of cos a?

Answer 4

\[\cos(a) = -{4\sqrt{11} \over 45}\]