Question

what is the value of
$\ \textless \ br /\ \textgreater \ \frac{cos 45° +cos65°/sin65}{cos85°}$


flw me on Ig akshatdubey912
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Answer 1

Step-by-step explanation:

Let sin70⋅sin50−cos85⋅cos65=I

Using 2sinAsinB=cos(A+B)−cos(A−B)

2cosAcosB=cos(A−B)+cos(A+B)

We get,

I=21(cos20−cos120−cos150−cos20)

=21(−cos120−cos150)

=21(sin30+sin60)

=21(21+23)

=43+1

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