Geometry
# Sum and Difference Trigonometric Formulas

Which of the following is equal to

$\sin 56 ^ \circ \cos 17 ^ \circ - \cos 56 ^ \circ \sin 17 ^ \circ ?$

Which of the following is equal to

$\sin 29 ^ \circ \cos 31 ^ \circ + \cos 29 ^ \circ \sin 31 ^ \circ ?$

Using the Sine sum formula, what is the value of

$\sin 75 ^ \circ ?$