Question

Write in terms of sine and cosine and simplify the expression.

sinA- 2cosAsinA divide by sin^2(A)-cos^2(A)+cosA-1

Answer 1

\[\frac{sinA-2cosAsinA}{\sin^2A-\cos^2A+cosA-1}\]

Answer 2

\[\frac{sinA(1-2cosA)}{1-\cos^2A-\cos^2A+cosA-1}\]

Answer 3

\[\frac{sinA(1-2cosA)}{-2\cos^2A+cosA}=\frac{sinA(1-2cosA)}{cosA(-2cosA+1)}\]

Answer 4

\[=\frac{sinA}{cosA}\]

Answer 5

any questions

Answer 6

how did you get the 1 on the bottom?

Answer 7

1-2cosA=-2cosA+1

they cancel
addition is commutative

Answer 8

examples:

3+2=2+3

3+(-2)=-2+3

Answer 9

i see... okay.

Answer 10

did you see i wrote sin^2A as 1-cos^2A

Answer 11

is that because its an identity?

Answer 12

yes!

Answer 13

thank you

Answer 14

np
well you know sin^2a+cos^2a=1
right
i just subtracted cos^2a on both sides to obtain
sin^2a=1-cos^2a