Answer:
a₂₁ = 638
Step-by-step explanation:
substitute n = 21 into the explicit formula
a₂₁ = - 2 + 32(21 - 1) = - 2 + 32(20) = - 2 + 640 = 638
The ratio A/r² would represent

which is the circumference of a circle divided by its diameter.
You can see this because the area of a circle is

r² and if you divided that by the radius squared, you are given pi which is the circumference of a circle divided by its diameter.
Given:
• AD = 3
,
• DC = 27
,
• BD = x + 3
Let's solve for x.
To solve for x, apply the altitude formula:

Where BD is the altitude.
Cross multiply:

Plug in the values and solve for x:

Take the square root of both sides:

Therefore, the value of x is 6 .
ANSWER:
d. 6