Answer:
- Exact Area = 210.25pi - 210
- Approximate Area = 450.185
The units for the area are in square inches or in^2. The approximate value shown above is when using pi = 3.14
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Explanation:
Use the pythagorean theorem to find the length of the hypotenuse
a^2 + b^2 = c^2
20^2 + 21^2 = c^2
400 + 441 = c^2
c^2 = 841
c = sqrt(841)
c = 29
The hypotenuse is 29 inches long. This is the diameter of the circle. Half of that is the radius at r = d/2 = 29/2 = 14.5 inches.
The area of the circle is...
A = pi*r^2
A = pi*(14.5)^2
A = pi*210.25
A = 210.25pi
Which is exact in terms of pi
We'll subtract off the triangular region as this isn't shaded in. The area of the triangle is base*height/2 = 20*21/2 = 420/2 = 210 square inches.
So the shaded region is therefore 210.25pi - 210 square inches
This approximates to 210.25*3.14 - 210 = 450.185 when using the approximation pi = 3.14; use more decimal digits of pi to get a more accurate value.
Answer:
86%
Step-by-step explanation:
Let g represent the mean mark for the 10 girls in the class. Then the mean mark for the class was ...
10g +20(62%) = 30(70%)
g = 3(.7) -2(.62) . . . . . . . . . divide by 10 and subtract 2(.62)
g = .86 = 86%
The mean mark for girls was 86%.
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You can do this in your head if you consider it in terms of deviations from the mean. The second equation above can be rewritten and factored as ...
g = 70% +2(70% -62%)
That is, because there are 2 boys for every girl, the girl's score is above the mean by an amount that is 2 times the amount that the boy's score is below the mean. The boys' score is below by 8%, so the girls' score is above by 16%, so is 86%.
Answer:
240 cm^3
Step-by-step explanation:
Volume of a rectangular prism = base area x height
the base is a rectangle, thus base area = width x length = 4 x 5 = 20 cm^2
20cm^2 x 12 = 240 cm^3
Answer:
Find the radius
Square the radius
Multiply by pi
Round to nearest hundredth
