Question #32016

2 Answers
Aug 15, 2015

Refer below

Explanation:

cos((3pi)/2 + x)
= cos(-pi/2 + x) (because cos x = cos (x+2pi))
= cos (pi/2 - x) (because cos (-x) = cos x)
= sin x
= 0.3

Aug 15, 2015

The answer is cos((3pi)/2+x) = 0.3. Here is a different path than Joel Kindiak's to the same answer.

Explanation:

Use the cosine of a sum formula:

cos((3pi)/2+x) = cos((3pi)/2)cos(x)-sin((3pi)/2)sin(x)

= (-1)cos(x) - (-1)(0.3)

= 0.3