Question

If A= 60° B= 30°then show that Cos (A+B)= Cos A Cos B - SinA SinB

plz...solve the correct answer
this for exam preparation
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Answer 1

Step-by-step explanation:

LHS =cos(A+B)=cos(60o+30o)=cos90o=0

RHS =cosAcosB−sinAsinB

        =cos60ocos30o−sin60osin30o

        =21×23−23×21=43−43=0

∴  LHS = RHS