Without using mathematical tables or calculator , show that

satisfies the equation

.

Thanks for ur help .

Printable View

- August 9th 2009, 02:26 AMthereddevilstrigonometry (1)Without using mathematical tables or calculator , show that

satisfies the equation

.

Thanks for ur help . - August 9th 2009, 03:24 AMMoo
Hello,

Consider :

------------------------------------------------------

Remember these identities :

Multiply them :

------------------------------------------------------

Hence

And if , then

So (1)

Now notice that :

and are both in the first quadrant (because )

So and

Hence

And it follows from (1) that if

Looks clear to you ? - August 9th 2009, 03:34 AMmr fantastic
- August 9th 2009, 04:57 AMthereddevils