Answer: a^3+81ab^2
First, you square (a+9b) which will become (a^2+81b^2)
Then, you multiply it by a and you will get a^3+81ab^2
Answer: Pi · 2r
Step-by-step explanation:
The standard formula to find the circumference of a circle is Pi times the diameter of the circle. The diameter is 2 times the radius, which is what you're going to use in the formula.
So instead of Pi times the diameter, we have Pi times 2 times the radius. Thus, the formula is Pi · 2r.
The formula for circumference = 2*Pi*r
R= radius. Radius is half of the diameter, and d= 20. This means that radius = 10. Now we have a full formula to work with.2*Pi*10.
Substitute 3.14 for pi.
3.14 * 10 = 31.4.
31.4*2 = 62.8.
62.8 rounded equals 63.
C = 63.
