Question

find the sum cos^2(j) + sin^2(j), if j = p/3
-do I have to use a pythagorean identity?

Answer 1

The easiest way to proceed with this is to recognize that cos^2(x) + sin^2(x) = 1.

So, no matter what x is, even if it is p/3, the sum is 1.

Pythagorean thm works - think of the unit circle:

hypotenuse (or radius) is always 1 on the unit circle, so c^2 = a^2 + b^2 is the same as hyp^2 = cos^2 + sin^2 - right?

Answer 2

Thanks I was using it and getting 1 as the answer but since I have to plug in six more of the "p" fractions with different denominators I thought it didn't make since that for each one would be 1

Answer 3

they're just trying to drive the idea home with a hammer

your first instincts were right on target

Answer 4

sorry - lost my name somewhere along the way