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
Answer:
3.1 inches
Step-by-step explanation:
Area of the cookie =Pi r^2
Pi = 3.14
Diameter = 2inches
Radius r = diameter/2 = 2/2
= 1
Therefore
Area = 3.14 x 1^2
= 3.14 x 1 x 1
= 3.1 inches
Hey there!
D is the answer.
I was thinking it might be B but no one said the lines crossed each other.
Hope this helps, Jesus loves you!
Complete question :
A bookstore manager marks down the price of older hardcover books, which originally sell for b dollars, by 52%.
a. Write the markdown as a decimal. b. Write an expression for the sale price of the hardcover book.
Answer:
0.52 ; 0.52b
Step-by-step explanation:
The markdown percentage = 52%
Expresaing markdown as a decimal :
52% = 52 / 100 = 0.52
Expression for the sale price of hardcover book:
Original price = b
Price was marked down by 0.52
Hence, sales price becomes ;
Original price * markdown
b * 0.52
0.52b
