JEE Main20205 Sep 2020Evening ShiftMathematicsTrigonometric Ratios & IdentitiesActual
If L = sin 2 π 16 - sin 2 π 8 and M = cos 2 π 16 - sin 2 π 8
Options
- AL = - 1 2 2 + 1 2 cos π 8
- BL = 1 4 2 - 1 4 cos π 8
- CM = 1 4 2 + 1 4 cos π 8
- DM = 1 2 2 + 1 2 cos π 8
Correct answer
D. M = 1 2 2 + 1 2 cos π 8
Step-by-step solution
L = sin π 16 + π 8 sin π 16 - π 8 = sin 3 π 16 · sin - π 16 = 1 2 cos 3 π 16 + π 16 - cos 3 π 16 - π 16 = 1 2 1 2 - cos π 8 M = cos π 16 + π 8 cos π 16 - π 8 = cos 3 π 16 · cos - π 16 = 1 2 cos 3 π 16 + π 16 + cos 3 π 16 - π 16 = 1 2 1 2 + cos π 8