Isidro L. answered 04/17/19
AP Calculus AB /Algebra Teacher 20 years Experience.
2sinx-cotx-csx=0 The first thing you have to do is convert cot(x )in terms of cos(x)/ sin(x) and csc(x) in terms of 1/sin (x). Let do these substitution to see how the trigonometric equations is transformed:
2 sin (x) - cos (x)/sin(x) - 1/sin(x) =0
Multiplying each term by the common denominator sin (x) we got:
2 sin^2(x) -cos (x) -1 =0. but I notice that sin^2(x) = 1-cos^x , let substitute this identity now
2(1-cos^2(x)) -cos(x) -1 =0 Now I see that every thing is in term of cos(x).
2-2cos^2(x) -cos (x) -1=0. adding 2 and -1 =1
-2cos^2(x)-cos(x) +1 =0. multiplying each term by -1
2cos^2 (x)+cos (x) -1 =0. Factoring
(2cos. - 1 ) ( cos (x). +1) =0. Applying property of zero
2cos(x) -1. =0.
cos (x) - 1/2=0 The angle x that correspond to 1/2 in the unit circle is 60 degrees or pi/3 and 300 degrees or 5pi/3.
For the second factor (cos(x) +1) =0
cos(x) =-1. The angle that correspond to -1 in the unit circle is 180 degrees or pi.
Therefore the answer to this problem is : pi/3, 5pi/3 and pi. Between 0≤x≤2∏