Question

2tan^2x-tanx-1=0
0<x<2pi

•MATH - Steve, Thursday, July 18, 2013 at 11:48am
(2tanx+1)(tanx-1) = 0
tanx = -1/2 or 1
...
Recall in which quadrants tanx is positive or negative

....................would x= 5pi/6,11pi/6,pi/4 and 5pi/4???

Answer 1

no, arctan(1/2) = .46
so, x = pi+.46 or 2pi-.46

the pi/4 and 5pi/4 are correct

(arcsin(1/2) = pi/6, not arctan(1/2))

Answer 2

small typo, I am sure Steve meant to type

x = <b>π - .46</b> or 2π-.46 , since the tan is negative in II and IV

Answer 3

Good catch - what was I thinking?
But then, I'm sure Robin knew that...

Answer 4

in radians what would the .46 be?

Answer 5

That IS in radians.