1.

Sin 45 sin 30+ cos 40cos 30 find

Answer»

Step-by-step explanation:

Given that

SIN 45°Sin30°+Cos45°Cos 30°

=>(1/√2)(1/2)+(1/√2)(√3/2)

=>(1/2√2)+(√3/2√2)

=>(1+√3)/2√2

Sin 45°Sin30°+Cos45°Cos 30°

Cos45°Cos 30°+Sin 45°Sin30°

Here, A=45° ,B=30°

This is in the form of

Cos A Cos B+Sin A Sin B

We know that

Cos A Cos B+Sin A Sin B=Cos(A-B)

Cos45°Cos 30°+Sin 45°Sin30°=Cos(45°-30°)=Cos15°

Cos 15°=(1+√3)/2√2


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