Question

How do you calculate sin or cos using radicals and not using a calculator.

Answer 1

What do you mean?

Answer 2

sorry,sin 30 is .5...how do you get that?

Answer 3

Do you know about special triangles? 45-45-90 and 30-60-90 triangles?

Answer 4

ok, im working on coterminal angles....so tangent 390 coterminal angle is 30...then it asks for tan30 degree as a radical.

Answer 5

@jevers01 you can calculate it easily through any metdology without remembering the formulas .first of all you need to do that.

Answer 6

what?

Answer 7

thats the type of stuff im working on

Answer 8

i just dont undertand how you can get an equation from sin, cos, or tangent.

Answer 9

You have to form triangles...do you know how to do that within unit circles?

Answer 10

NOPE

Answer 11

Well, that's sort of an entire lesson to explain on here...I would suggest watching KhanAcademy videos on Trigonometry to help you through the basics

Answer 12

here, try this ...sec of 390 is 2*sqrt3 / 3...how is that? where does those numbers come from?

Answer 13

\[\frac{1}{\cos 390}\]
The reference angle is 30 degrees so cos 30 degrees is \[\frac{\sqrt{3}}{2}\] So now you have \[\frac{1}{\frac{\sqrt{3}}{2}} = \frac{2}{\sqrt{3}}\]

If you rationalize the denominator, you'll get 2*sqrt3 / 3

Answer 14

I know cos 30 degrees is that from memory, but you can work out special triangles manually, it just takes longer

Answer 15

ok i think i might finally get it...

Answer 16

by george i think i got it lol...I was trying to solve for cotangent before solving for tangent...

Answer 17

thank you very much