Well, you have to do it with the substitution method now it's not easy, it takes some time to get used to it. I'm not really sure how to explain it but if you go on Khan Academy it will show you how to do it.
Yeah that's right I'm pretty sure that's the work u do so u r not wrong ok so relax
Answer with explanation:
The given trigonometric Function is,
y= cos x
→The maximum value of , cos x , is 1, at x=0 degree.
Cos x =1
→Cos x = Cos (0)degree,

→ for, k= An Integer
x=2 k π→→General formula that gives the x-coordinates of the maximum values for y = cos(x)
Ordered Pair =(x,y)=(2 k π, 1)
For, any value of , k in the given equation, y will be always 1.
2radical 10 for simplifying radical 40
49.617 ( alternative form )