Given:
Choose a number between 0 and 20.
If the difference is less than 10 then Eric wins.
Let us x is Eric's number. 0 <u><</u> x <u><</u> 20
If Eric wins. |x -7| < 10
|x-7| < 10 → -10 < x-7 < 10 → -10 + 7 < x - 7 + 7 < 10 + 7 → -3 < x < 17
Taking into account that the number must be given between 0 and 20.
0 <u><</u> x <u><</u> 20
-3 < x < 17
→ 0 < x < 16
Answer:
see explanation
Step-by-step explanation:
Using the trigonometric identity
sin²x + cos²x = 1
Consider the left side
2cos²A - 1 ← replace 1 by sin²A + cos²A
= 2cos²A - ( sin²A + cos²A)
= 2cos²A - sin²A - cos²A
= cos²A - sin²A = right side ⇒ verified
Answer:
8 Books
Step-by-step explanation:
First find how many she had before buying 8 more-
12 - 8 = 4
Then multiply that by 2
4 x 2 = 8
The had 8 books to begin with