Question

how to solve....i am unable to solve even after applying the formula​

Answer 1

Answer:

1

Step-by-step explanation:

Your answer is one .

Approach : A+B+C+D = 2π

A+B = 2π - (C+D)

Applying Cos function to both sides,

CosACosB - SinASinB = Cos[2π - (C+D)]

CosACosB - SinASinB = Cos(C+D)

CosACosB - SinASinB = CosC*CosD - SinC*SinD

CosACosB + SinC*SinD

= CosC*CosD + SinASinB