Answer:
Step-by-step explanation:
let cos^{-1}x=t
cos t=x
when x=1,cos t=1=cos 0
t \rightarrow 0

Answer:
13²+4−1
Step-by-step explanation:
<em><u>hope it helps</u></em>
X² - 4x - 77 = 0
( x + 7) ( x - 11)
x + 7 = 0
x - 11 = 0
x = -7
x = 11
-5=-2/9x.
x=22.5 / x=45/2