Dom's blog # 1

Chapter 8-5
Divide by a trig function when solving to cancel.
Cancel from the inside of a trig function.
Ex: sin(2x)/2 = you CAN'T cancel the 2
Ex:
1)2sin^2 theta-1=0
2sin^2 theta=1
sin^2 theta=1/2
sin theta = /- sq.root of 1/2
theta= sin inverse (sq. root of 1/2)
2)sin^2x-sinx=cos^2 x
sin^2x-sinx=1-sin^2x
2sin^2x-sinx-1=0
(2sin^2 x -2sinx) (sinx-1)=0
2sinx(sinx-1) (sinx-1)=0
(2sinx 1)(sinx-1)=0
2sinx 1=0 sinx-1=0
sinx=-1/2 sinx=1
x=sin inverse (1/2) x=sin inverse (1)
x=7π/6,11π/6,π/2 x=π/2
3)sinxtanx=3sinx
sinxtanx-3sinx=0
sinx(tanx-3)=0
sinx=0 tanx-3=0
x=sin inverse(0) x=tan inverse (3)