SSC CPO SI and ASI Model Paper 1

Question : 129 of 200

Marks: +1, -0

Find out the value of $sin^2$ 10° + sin2 20° + sin2 30°………+ sin2 80° + sin2 90°.

Solution:

(3)

sin^{2}10° + sin^{2}20° + sin{2}30° + …+ sin^{2}80° + sin^{2}90°

= sin^{2}10° + sin^{2}20° + sin^{2}30° +sin^{2}40° + sin^{2}50° + sin^{2}60° +sin^{2}70° + sin^{2}80° + sin^{2}90°

= sin^{2}10° + sin^{2}20° + sin^{2}30° +sin^{2} 40° + sin^{2} (90° – 40°) + sin^{2}(90° – 30°) + sin^{2} (90° – 20°) +sin^{2} (90° – 10°) + sin^{2} 90°

= sin^{2}10° + sin^{2}20° + sin^{2}30° +sin^{2}40° + cos^{2}40° + cos^{2}30° +cos^{2}20° + cos^{2}10° + sin^{2}90°

= 4 + 1 = 5

Go to Question:

Prev Question

Next Question