Question

plse need it urgent
find the value of

sin18degree-sin66degree+sin60 degree

Answer 1

sin12degree

Answer 2

wrong @sjerman1

Answer 3

hmm lame well lets take the actual values of sin18-sin66+sin60 (degrees) and find out what it comes out to

Answer 4

Do you want an exact value?

Answer 5

but find the value without calculator

Answer 6

hmmm

Answer 7

You can re-write it as such:

Answer 8

well the exact value is .2614969405 but sorry that doesnt help

Answer 9

@edlevin
how ur cos(2pi/15) came, plse explain

Answer 10

If you convert it from degree to radians, also sin and cos are related but shifted by a phase.

Answer 11

This explains it well:

http://www.mathwarehouse.com/trigonometry/radians/convert-degee-to-radians.php

Answer 12

so what after that
i mean how to solve next

Answer 13

I mean if you are very good at math in your head you could get an estimate value, you are suppose to solve that entire problem to a decimal without using a calculator?

Answer 14

i know , what about cos(2pi/15)

Answer 15

That will just come out to be a complex decimal, thats as simplified as you can get.

Answer 16

I suppose you could write it like this...

But that is VERY messy...

Answer 17

brother , i m asking about cos(2pi/15)

Answer 18

That eqn2 I posted is a different version of writting cos(2pi/15)

Answer 19

hoow u came to know the value of cos(2pi/15)

Answer 20

Using various trig identities

http://en.wikipedia.org/wiki/List_of_trigonometric_identities

Answer 21

i m confused over thispart
sin66degree=cos24degree-------------------?

Answer 22

then u tell me the value which i didn;t understand