csat-suneung 2018 Q7

csat-suneung · South-Korea · csat__math-science 3 marks Quadratic trigonometric equations
When $0 \leq x < 2 \pi$, what is the sum of all solutions to the equation $$\cos ^ { 2 } x = \sin ^ { 2 } x - \sin x$$ ? [3 points]
(1) $2 \pi$
(2) $\frac { 5 } { 2 } \pi$
(3) $3 \pi$
(4) $\frac { 7 } { 2 } \pi$
(5) $4 \pi$
When $0 \leq x < 2 \pi$, what is the sum of all solutions to the equation
$$\cos ^ { 2 } x = \sin ^ { 2 } x - \sin x$$
? [3 points]\\
(1) $2 \pi$\\
(2) $\frac { 5 } { 2 } \pi$\\
(3) $3 \pi$\\
(4) $\frac { 7 } { 2 } \pi$\\
(5) $4 \pi$