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Question

Mathematics Question on Trigonometric Functions

Sin2  17.5+Sin2  72.5Sin^2 \; 17.5^{\circ} + Sin^2 \; 72.5^{\circ} is equal to

A

tan245tan^2 45^\circ

B

Cos290Cos^2 90^\circ

C

Sin2  45Sin^2 \; 45^\circ

D

Cos2  30Cos^ 2 \; 30^\circ

Answer

tan245tan^2 45^\circ

Explanation

Solution

We have, sin217.5+sin272.5\sin^2 \,17.5^{\circ} + \sin^2 \, 72.5^{\circ} =sin217.5+sin2(9017.5)= \sin^2 \, 17.5^{\circ} + \sin^2(90^{\circ} - 17.5^{\circ}) =sin217.5+cos217.5= \sin^2 \, 17.5^{\circ} + \cos^2 \,17.5^{\circ} =1=12= 1 = 1^2 =tan245= \tan^2 \, 45^{\circ}