SOLUTION: Please help! Do not understand!! Find the solutions of the given equation in the indicated interval. (Give your answers to two decimal places. Enter your answers as a comma-separa

Algebra ->  Trigonometry-basics -> SOLUTION: Please help! Do not understand!! Find the solutions of the given equation in the indicated interval. (Give your answers to two decimal places. Enter your answers as a comma-separa      Log On


   

Question 963709: Please help! Do not understand!!
Find the solutions of the given equation in the indicated interval. (Give your answers to two decimal places. Enter your answers as a comma-separated list.)
20 (cos(x))^2 + cos(x) − 1 = 0, [0, π]
Answer by lwsshak3(11628) About Me  (Show Source):
You can put this solution on YOUR website!
Find the solutions of the given equation in the indicated interval. (Give your answers to two decimal places. Enter your answers as a comma-separated list.)
20 (cos(x))^2 + cos(x) − 1 = 0, [0, π]
***
20cos%5E2%28x%29%2Bcosx-1=0
solve for cosx by quadratic formula
cosx+=+%28-b+%2B-+sqrt%28+b%5E2-4%2Aa%2Ac+%29%29%2F%282%2Aa%29+
a=20, b=1, c=-1
ans:
cosx=-0.25
x=1.82 radians
or
cosx=0.2
x=1.37 radians