Question

Evaluate without using tables: (cos47/sin 43)^2 + (sin 72/cos 18)^2 -2 cos^2 45.


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Answer 1

Answer:

sin(43)=sin(90-47)= cos47

cos(18)= cos(90-72) = sin72

cos45 = 1/sqrt 2

= (1)^2 +(1)^2 -1

=1