csat-suneung 2021 Q16

csat-suneung · South-Korea · csat__math-humanities 4 marks Quadratic trigonometric equations
For $0 \leq x < 4 \pi$, what is the sum of all solutions to the equation $$4 \sin ^ { 2 } x - 4 \cos \left( \frac { \pi } { 2 } + x \right) - 3 = 0$$ ? [4 points]
(1) $5 \pi$
(2) $6 \pi$
(3) $7 \pi$
(4) $8 \pi$
(5) $9 \pi$
For $0 \leq x < 4 \pi$, what is the sum of all solutions to the equation
$$4 \sin ^ { 2 } x - 4 \cos \left( \frac { \pi } { 2 } + x \right) - 3 = 0$$
? [4 points]\\
(1) $5 \pi$\\
(2) $6 \pi$\\
(3) $7 \pi$\\
(4) $8 \pi$\\
(5) $9 \pi$