Question

-sin^2x=2cos x-2

Answer 1

\(\bf \textit{recall that}\\ \quad \\
sin^2(\theta)+cos^2(\theta)=1\implies cos^2(\theta)=1-sin^2(\theta)\)

Answer 2

@jdoe0001 what comes next i am lost

Answer 3

well... aren't you just verifying identities?

Answer 4

no i am solving the equation

Answer 5

.... oh... shoot.. that identity there... is the wrong one =(

Answer 6

its okay can you help me solve it though?

Answer 7

@primeralph

Answer 8

\(\bf \textit{recall that}\\ \quad \\
sin^2(\theta)+cos^2(\theta)=1\implies sin^2(\theta)=1-cos^2(\theta)\qquad thus\\ \quad \\

-sin^2(x) = 2cos(x)-2\implies -(1-cos^2(x))=2cos(x)-2\\ \quad \\
-1+cos^2(x)=2cos(x)-2\implies cos^2(x)-2cos(x)+1=0
\)

as you can see, it's just a quadratic

Answer 9

thank you i got it now

Answer 10

yw