Задание № 3 а) Решите уравнение \( 36^{\sin 2 x}=6^{2 \sin x} \). б) Найдите все корни этого уравнения, принадлежащие отрезку \( \left[-\frac{7 \pi}{2} ;-\frac{5 \pi}{2}\right] \)

a) \( \cos ^{2} x-3 \operatorname{sen}^{2} x=0 \) b) \( \cos 2 x=1+4 \operatorname{sen} x \)

a) \( \cos ^{2} x-3 \operatorname{sen}^{2} x=0 \)

\( A B C \) is a triangle. \( A C K K \nabla .9 \mathrm{~cm} \) Angle \( B=90^{\circ} \) Angle \( C=38^{\circ} \) Calculate the length of \( B C \). Give your answer correct to 3 significant figures

\( A B C \) is a triangle. \( A C K K .9 \mathrm{~cm} \) Angle \( B=90^{\circ} \) Angle \( C=38^{\circ} \) Calculate the length of \( B C \). Give your answer correct to 3 significant figures.

Triangle \( P Q R \) has a right angle at \( Q \). \( P Q=3.4 \mathrm{~cm} \) and \( P R=5.8 \mathrm{~cm} \). Work out the size of angle \( Q R P \). Give your answer correct to 1 decimal place.