Answer:
The circumference of the circle is 28.26 inches.
Step-by-step explanation:
If you think about it in retrospect, circles must have been hard to find the perimeter of in the old math days. They weren't straight like squares, so it must have been really hard to approximate what the perimeter would have been for a circle.
Luckily, these days, we don't have to worry about that anymore. Now we know that the perimeter of a circle, also known as the circumference, can be found with the following formula:
where is a constant;
and d is the diameter of a circle.
The diameter of a circle, in my own words, is the length of a line that intersects the center of the circle as well as two points on that circle. Half of the diameter is also known as the radius.
Luckily, for this problem, we're already given and the diameter <em>d</em>, so we just have to plug them in to find the circumference.
Therefore, without rounding, the circumference of the circle is 28.26 inches.
Answer:
x ∈ [-2, 7]
Step-by-step explanation:
The given equation ...
x^2 -5x -4 ≤ 10
can be rewritten as ...
x^2 -5x -14 ≤ 0
and factored as ...
(x +2)(x -7) ≤ 0
Clearly, the "or equal to" condition will be met when x=-2 and x=7. For values of x between these numbers, one factor is negative and the other is positive. Hence the product will be negative. So, numbers in that interval are the solution set.
x ∈ [-2, 7]
