# How do you express #cos(pi/ 3 ) * sin( ( 5 pi) / 8 ) # without using products of trigonometric functions?

##### 2 Answers

It may be "cheating", but I would just substitute

#### Explanation:

You're probably supposed to use the identity

Put in

Then

where in the last line we use

As you can see, this is unwieldy compared with just putting in

#### Explanation:

Trig table -->

Trig unit circle and property of complementary arcs -->

P can be expressed as:

NOTE. We can evaluate