cos (2x) = cos x
2 cos^2 x -1 = cos x using the double angle formula
2 cos ^2 x -cos x -1 =0
factor
(2 cos x+1) ( cos x -1) = 0
using the zero product property
2 cos x+1 =0 cos x -1 =0
2 cos x = -1 cos x =1
cos x = -1/2 cos x=1
taking the arccos of each side
arccos cos x = arccos (-1/2) arccos cos x = arccos 1
x = 120 degrees x=-120 degrees x=0
remember you get 2 values ( 2nd and 3rd quadrant)
these are the principal values
now we need to add 360
x = 120+ 360n x=-120+ 360n x = 0 + 360n where n is an integer
Since one side is 40°, you subtract that from 180.
180° - 40°= 140°.
So therefore your missing side lengths are 140, 40, and 140.
hopefully this helps
Answer:
Ang mga Babae sa Relihiyon at Pilosopiya sa Asya. Limang Ugnayan. emperador-mamamayan. ama-anak na lalaki.
After 10 hours the temperature is shown on the graph as 30 degrees.
50 degrees - 30 degrees = 20 degrees.
The temperature dropped 20 degrees in 10 hours.
Divide the change by the time:
20 degrees / 10 hours = 2 degrees per hour.
Because the temperature dropped, the change would be negative.
The answer is D. -2 degrees per hour.
