Question

How do I evaluate cos(1) without a calculator?
I know cos(0), because zero degrees on the unit circle has the coordnate (1,0), but I don't see a 1 degree or radian on the unit circle anywhere??

Answer 1

evaluate in terms of what exactly?

Answer 2

he means in terms of radians.

Answer 3

Use a Taylor series to approximate the cosine function
\[\cos x = 1 - \frac{x^2}{2} + \frac{x^4}{24} -\frac{x^6}{720} ...\]
Make sure you use radians, so if you want cos of 1 degree, plug in x = (pi/180)

Of course, you have to use your calculator to evaluate the polynomial as well ...