Question

Cosb= A. cosb B. sina C. cosa OD. sinb [sin (a + b) + sin(a - b)] OOO MONETHE

Answer 1

Answer: B. sin a

Step-by-step explanation

• Expression,

`_(---)\cos b=(1)/(2)\left[\sin\left(a+b\right)+\sin\left(a-b\right)\right]`

If we use the properties we get that:

`2\sin a\cos b=\left[\sin\left(a+b\right)+\sin\left(a-b\right)\right]`

Then:

`\sin a\cos b=(1)/(2)\left[\sin\left(a+b\right)+\sin\left(a-b\right)\right]`