Question

if A+ b =45° then (cos A.cosB- sinA.sinB) is​

Answer 1

Answer:

1/✓2

Step-by-step explanation:

we know that

cos(A+B)= cosAcosB-sinAsinB

so,

(cos A. cosB- sinA. SinB)

= cos(A+B).

=cos(45°). {given, A+B=45°}

=1/✓2. {since, cos45°=1/✓2}