Hello, Dragon08!
We need this identity: .Given that ,
determine the following to four decimal places, without using a calculator.
. .
. . . . . .
We need this identity: .
. . . . . .
Given that tan 4pi/9=5.6713, determine the following, to four decimal places, without using a calculator. a)cot(pi/18) b)tan(13pi/9)
I got a by using a cofunction identity:
cot(pi/18)= tan(pi/2-pi/18)
=tan(4pi/9)
=5.6713
But I don't know how to do b. What formula do I use?