Question

Simplify the expression using sum or difference identities cos(12)cos(-3)-sin(12)sin(-3)​

Answer 1

when you simplify the answer is -0.91113026

Explanation:

Answer 2

`\cos(12)\cos(-3)-\sin(12)\sin(-3)​=0.98`

Explanation:

Given : Expression
`\cos(12)\cos(-3)-\sin(12)\sin(-3)`

To find : Simplify the expression ?

Solution :

Expression
`\cos(12)\cos(-3)-\sin(12)\sin(-3)`

We know the trigonometry identity,

`\cos A\cos B-\sin A\sin B=\cos (A+B)`

Here, A=12 and B=-3

`\cos(12)\cos(-3)-\sin(12)\sin(-3)=\cos(12+(-3))`

`\cos(12)\cos(-3)-\sin(12)\sin(-3)=\cos(12-3)`

`\cos(12)\cos(-3)-\sin(12)\sin(-3)​=\cos(9)`

From calculator,
`\cos 9=0.98` in degrees.

Therefore,
`\cos(12)\cos(-3)-\sin(12)\sin(-3)=0.98`