Trig questions

Question

I am getting stuck at 7 plus or minus sqrt 309 / 26

 

13sin^2x-7sinx=5

solve for interval [0,360degrees] 

Answer 1

the result of using quadratic formula to solve for sin x is CORRECT, IF YOU put parentheses around everything preceding " / 26."

This gives sin x = about { 0.9453, -0.40686}

 

Using arcsin on the first decimal number gives you x about 70.97 degrees. Also 180 - that, because sines in first quadrant also appear in second quadrant.

 

Using arcsin on the second decimal number, =0.40686, gives about -24 degrees. Expressed in positive form for that 4th quadrant angle, you get about 336 degrees. An also you get a corresponding angle in quadrant three, which is180+24 degrees.

 

I leave it to you to CHECK THESE RESULTS (all four) on your calculator.