is it right to say that cos (a+b)=cosA+cosB
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cos (a+b)=cosA+cosB
here a, b, A, B all are different angle
so this is possible or not we decide from some assumption.
let a=30 degree
b=60degree
A=45 degree
B=90 degree
now
cos (a+b)=cos (30+60)=co90=0
cosA+cosB=cos45+cos90=1/root2
LHS not equal RHS
so it is wrong .
if your question
cos(A+B)=cosA+cosB
again asume A and B numerical value
i.e. A=30
B=60
LHS=cos (30+60)=cos90=0
RHS=cosA+cosB=cos30+cos60
=1/2+root3/2
here we see
LHS is not RHS hence it is also wrong
cos (a+b)=cosA+cosB
here a, b, A, B all are different angle
so this is possible or not we decide from some assumption.
let a=30 degree
b=60degree
A=45 degree
B=90 degree
now
cos (a+b)=cos (30+60)=co90=0
cosA+cosB=cos45+cos90=1/root2
LHS not equal RHS
so it is wrong .
if your question
cos(A+B)=cosA+cosB
again asume A and B numerical value
i.e. A=30
B=60
LHS=cos (30+60)=cos90=0
RHS=cosA+cosB=cos30+cos60
=1/2+root3/2
here we see
LHS is not RHS hence it is also wrong
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