First find the area of the circle using A=pi*r^2
pi*36
Then divide this by 4 because the shaded region is 1/4 of the circle
(36*pi)/4=9*pi
Final answer: B
Answer:
960
Step-by-step explanation:
We start with the variable "x". Let's call "x" Raina's penny bank.
After adding 360 pennies, at the end, she has 5/8x, or 5/8.
So we start with
(1/4)x + 360 = 5/8x
Let's subtract 1/4x from both sides
360 = 5/8x - 1/4x
Remember, we need to use common denominators to subtract, so 1/4 becomes 2/8
360 = 5/8x - 2/8x
Now we simplify to get
360=3/8x
Multiply the reciprocal of 3/8 to both sides which is 8/3
360 * 8/3 = x
Answer is 960 pennies.
Therefore Raina's bank hold 960 pennies.
We can use linear combinations of the equations to eliminate variables.
3x - 4y = 1
-2x + 3y = 1
To eliminate y we'll make the linear combination of 3 times the first equation minus four times the second.
9x - 12y = 3
-8x + 12y = 4
Adding,
x = 7
We could solve for y directly but let's use another linear combination, twice the first plus three times the second:
2(3x - 4y) + 3(-2x + 3y)= 2(1)+3(1)
y = 5
Check: 3(7)-4(5)=1 good. -2(7)+3(5)=1 good.
Q18 Answer: (7,5)
y = -3x + 5
5x - 4y = -3
4y +1(5x - 4y) = 4(-3x + 5) + 1(-3)
5x = -12x + 20 -3
17 x = 17
x = 1
y = -3(1) + 5 = 2
Check: 5(1) - 4(2) = -3 good
Q19 Answer (1,2)
6x + 5y = 25
x = 2y + 24
6x = 12y + 144
5y = 25 - 12y - 144
17y = -119
y = -119/17= -7
x = 2y+24= 10
Check: 6(10)+5(-7)=25 good 2y+24=2(-7)+24=10=x good
Q20 Answer (10,-7)
3x + y = 18
-7x + 3y = -10
9x + 3y = 54
9x - -7x = 54 - -10
16x = 64
x=4
y = 18 -3x = 18-12=6
Check: 3(4)+6=18 good, -7(4)+3(6)=-10 good
Q21 Answer: (4,6)
Since the measures of the two angles are in the ratio 8:1, this means the bigger angle's is 8x and the smaller angle is x. Since they are complementary, they add to 90°, so you create the equation 8x+x=90°. This can be simplified to 9x=90°. Then, you divide 90 by 9 to get 10. This means x=10. Next, you replace x with 10 to find the measure of the bigger angle. 8x10=80, so the larger angle is 80°.