Thread: Tangent Help

How do you find the tangent of an angle without a calculator?

Like a 30 degree angle, whats the diagram or proof for it?

thanks

Here you go...

thanks alot!

what about 15 degree?

15 degree is the value of 45 degree minus 30 degree

But you need special identities to calculate for example: sin(45 - 30)

but isnt there a way using a 30 60 90, mabe bisecting the 30 and finding out the tangent of 15..with no calc at all

Unfortunately no, not unless you have values for the sides.

There isnt really a shortcut.

thats what i have so far

Cos 15 will give you the value of bd.

Then Pythagoras will give you the value of ad.

And you are given that (root3)/2 = ad/dc.

So then you can calculate dc.

ahhh great idea

thanks

hha
now im simplifying

tan(15) = root( (root3/cos15)^2 - (root3)^2 ) / root3

but without solving the tans and cos and roots...(basically no calc at all)

It did take a lil good old trig to get there.

can i even simplify that besides change the root3^2 to 3?

Tan 15 = ad/root3

= (1/cos 15) - 1

I hope all this helped you.

it did

its all very appreciated!