| Your Results | Global Average | |
|---|---|---|
| Questions | 5 | 5 |
| Correct | 0 | 2.57 |
| Score | 0% | 51% |
A cylinder with a radius (r) and a height (h) has a surface area of:
2(π r2) + 2π rh |
|
4π r2 |
|
π r2h2 |
|
π r2h |
A cylinder is a solid figure with straight parallel sides and a circular or oval cross section with a radius (r) and a height (h). The volume of a cylinder is π r2h and the surface area is 2(π r2) + 2π rh.
The dimensions of this cylinder are height (h) = 2 and radius (r) = 9. What is the surface area?
| 198π | |
| 16π | |
| 20π | |
| 168π |
The surface area of a cylinder is 2πr2 + 2πrh:
sa = 2πr2 + 2πrh
sa = 2π(92) + 2π(9 x 2)
sa = 2π(81) + 2π(18)
sa = (2 x 81)π + (2 x 18)π
sa = 162π + 36π
sa = 198π
The formula for the area of a circle is which of the following?
c = π r2 |
|
c = π d2 |
|
c = π r |
|
c = π d |
The circumference of a circle is the distance around its perimeter and equals π (approx. 3.14159) x diameter: c = π d. The area of a circle is π x (radius)2 : a = π r2.
Order the following types of angle from least number of degrees to most number of degrees.
right, acute, obtuse |
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acute, obtuse, right |
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right, obtuse, acute |
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acute, right, obtuse |
An acute angle measures less than 90°, a right angle measures 90°, and an obtuse angle measures more than 90°.
Solve for c:
c2 - 6c - 27 = 0
| -3 or 9 | |
| 9 or -6 | |
| 7 or -7 | |
| -4 or -9 |
The first step to solve a quadratic equation that's set to zero is to factor the quadratic equation:
c2 - 6c - 27 = 0
(c + 3)(c - 9) = 0
For this expression to be true, the left side of the expression must equal zero. Therefore, either (c + 3) or (c - 9) must equal zero:
If (c + 3) = 0, c must equal -3
If (c - 9) = 0, c must equal 9
So the solution is that c = -3 or 9