Answer:
236.25 
Step-by-step explanation:
To get the area of the shaded portion, add up all the areas of the 3 quadrants
First, find the area of one quadrant
Area of a quadrant = 1/4 π
π = 3.14
Radius, r = 10 cm
A = 1/4 *3.14 * 
A = 1/4 *3.14 * 100
A = 1/4 *314
A = 78.75
Now, multiply by 3
3 * 78.75
= 236.25
The total amount of tax on her purchases is $378.47
I believe the answer is between 90-100.
Hopes this helps
Answer:
see explanation
Step-by-step explanation:
Using the trigonometric identity
2sinxcosy = sin(x + y) + sin(x - y) , then
with x = 70 and y = 20
2sin70cos20
= sin(70 + 20) + sin(70 - 20)
= sin90 + sin50
= right side , thus proven
