help me for ques no 18
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adithyaramapuram29:
I have given u the answer
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Answer:
Step-by-step explanation:
use identity
pura answer de do
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Ans=1
Numerator=cos^2 20°+cos^2 70°
= sin^2(90°-20°)+ cos^2 70°
=sin^2 70°+ cos^2 70°
=1
denominator=sec^2 50°- tan^2(90-40)
=sec^2 50°- tan^2 50
= 1
Numerator/denominator=1
Since , sin^2 a+ cos^2 a= 1
sec^2 a - tan^2 a = 1
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