Question
If tan A = 2 and A belongs to [pie,3pie/2] then the expression cos A divided by sin cubed A +cos cubed A is equal to what?
Answers
Steve
tanA = 2 in QIII means
sinA = -2/√5
cosA = -1/√5
cosA/(sin^3A + cos^3A)
= -1/√5 / (-8/5√5 - 1/5√5)
= -1/√5 / (-9/5√5)
= -1/√5 * -5√5/9
= 5/9
that's PI, not PIE!
sinA = -2/√5
cosA = -1/√5
cosA/(sin^3A + cos^3A)
= -1/√5 / (-8/5√5 - 1/5√5)
= -1/√5 / (-9/5√5)
= -1/√5 * -5√5/9
= 5/9
that's PI, not PIE!