Find all solutions in the interval -180o ≤ x ≤ 180o
to the equation cosx + (sin^2)x = 5/4
Hello,
The writing $\displaystyle \sin^2 x$ means $\displaystyle (\sin(x))^2$
Remember the identity : $\displaystyle \cos^2(x)+\sin^2(x)=1 \implies \sin^2(x)=1-\cos^2(x)$
The equation is now :
$\displaystyle \cos x+1-\cos^2 x=\tfrac 54$
$\displaystyle \cos^2 x-\cos x+\tfrac 14=0$
$\displaystyle (\cos(x)-\tfrac 12)^2=0$
Solve the final