Question

If A = 15°

Find 4 cos 2A . sin 4A .tan 3A - 1

• A. 3
• B. 2
• C. 4
• D. 0

Answer 1

The correct option is B

2

Given A = 15 °;

Hence 4 cos 2A . sin 4A .tan 3A - 1

= 4 cos 2(15) . sin 4(15) . tan 3(15) -1

= 4 cos 30° . sin 60° . sin 45° - 1

= 4$\frac{\sqrt{3}}{2}$ . $\frac{\sqrt{3}}{2}$ . 1 - 1

= 3 - 1

= 2