Question

the value of cos^2 10°- cos 10° cos 50°+ cos^2 50°
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Answer 1

Answer:

3/4

Step-by-step explanation:

cos^2 10°- cos 10° cos 50°+ cos^2 50°

=1/2(1+cos20°−(cos60°+cos40°)+1+cos100°)

=1/2(2+cos20°−1/2−cos40°+cos(180°−80°))

=1/2(3/2+cos20°−(cos80°+cos40°))

=1/2(3/2+cos20°−(2cos60°cos20°))

=1/2(3/2+cos20°−(2(1/2)cos20°))

=1/2(3/2+cos20°−cos20°)

=1/2⋅3/2

=3/4

​Thanks ...