6. Prove that (- ăź) + (COt20)-1cosec 70(cosec2 ,)2 +70)2:1Prove t – InterviewSolution

1.

6. Prove that (- ăź) + (COt20)-1cosec 70(cosec2 ,)2 +70)2:1Prove thatsec 70

Answer»

1/cosec 70 = sin 70

1/ sec 70 = cos 70

sin 70 = sin (90-20) = cos 20cos 70 = cos (90-20) = sin 20

so substitute all these and simplify

( sin 20 ) ^ 2 + ( cos 20 ) ^ 2 = 1as(sin x) ^ 2 + (cos x) ^ 2 = 1 for all x.

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