Question

How do you evaluate sine, cosine, tangent of `-pi/2` without using a calculator?

Answer 1

`"please look at animation below."`

Explanation:

#"first ,let us draw a unit circle. A unit circle is a circle with radius of 1."#

`" if "alpha=0, " then cosine=1, sine=0, tangent=0"`

`"if alpha="-pi/2 " then cosine=0, sine=-1, tangent="(-1)/0" undefined"`