Trig help (1 Viewer)

[coyazayo]

Find the set of values of x when 2sin^2x-sinx<0, where -270degrees(inclusive)<x<270degrees(inclusive)

Thank you

 

[davidgoes4wce]

Graphically (Shame that HSC don't allow NSW students to use graphics calculators)




Algebraically: ( Draw the 4 quadrants and determine which exact values that is below 1/2 or above 1/2)

 

[davidgoes4wce]

2nd line was wrong there it needed so show

sin x (2 sin x -1)=0

 

[davidgoes4wce]

For the quadrants , I should have looked at the angle anti-clockwise as well

 

[davidgoes4wce]

 

[davidgoes4wce]

Answers would be: (-2pi, -11pi/6) , (-7pi/6, -pi), (0, pi/6), (5pi/6, pi)

 

[davidgoes4wce]

or if you want it in degrees terms as stated in the question:

(-360 to -330), (-210 to -180), (0 to 30), (150 to 180 degrees)

 

[davidgoes4wce]

I came from a state where they allowed us to use graphics calculators, I think also VCE have a 'Calculator Assumed Section", as well as IB

 

[leehuan]

...

Woah. That's a ton of comments for one person needing help with one question.