trig
posted by lola on .
How do I get exact measures?
cosine 270 degrees
sin 90 degrees
tan 360 degrees
csc 45 degrees
no calculator!

The best way to solve these problems is to draw a unit circle (radius = 1), and calculate these ratios from the definitions (cosine = adjacent / hypotenuse, etc.)
The first three can be solved easily this way. The last one,
csc(45°)=1/sin(45°)
Knowing that sin(45)=cos(45), and
sin²(45)+cos²(45)=1, we solve for sin(45)=(√2)/2, so
csc(45)=2/√2 = √2.