$\"\"$

b) $\"italic$

The sum formula for the sine function: $\"italic$ .

Substitute $\"italic$ .

The values are available in problem no 33a.

$\"equal$

$\"equal$ (Simplify)

$\"equal$ (Rewrite the expression with common denominator)

$\"equal$ (Simplify) $\"\"$

The value of $\"italic$ $\"equal$ .