Answer:
(x + 4)^2 + (y - 8)^2 = 81
or
(x + 4)^2 + (y - 8)^2 = 9^2 depending on how your teacher wants it written.
Step-by-step explanation:
The standard form for a circle is
(x + h)^2 + (y + k)^2 = r^2
r is the radius.
You are given the diameter
r = d/2
r = 18/2
r = 9
So you already have the right hand side of the equation
(x + h)^2 + (y + k)^2 = 9*2
(x + h)^2 + (y + k)^2 = 81
You basically have h and k as well. They come from the center point.
h = 4
k = - 8
So the equation of the circle (and the answer) is
(x + 4)^2 + (y - 8)^2 = 81
One question remains. Why do the x and y values change signs? If you know what the distance formula is, then what you are finding is the distance r of all points on the circle from the center of the circle.
It is the distance formula that is actually the formula for the circle.
Given:
3 kids
72 is the product of their ages.
There is a youngest child.
This means that all three are of different ages. We need to factor 72 into 3 integers.
Let us use prime factorization:
72 ÷ 2 = 36
36 ÷ 2 = 18
18 ÷ 2 = 9
9 ÷ 3 = 3
Prime factors are: 2 x 2 x 2 x 3 x 3 OR 2³ x 3²
3 ages.
eldest = 3³ = 9
middle = 2² = 4
youngest = 2¹ = 2
2 x 4 = 8
8 x 9 = 72
30% of £10 = £3
30% discount = £10 - £3 = £7
Cake costs £7
