To determine the area if the circle, you must know the diameter or the radius of a circle.
If you know the radius of a circle, use this as your formula. Remember: Pi (the greek symbol thingy) is equal to 3.1415. (A is equal to area of the circle and r represents the radius)

If you know the diameter, just divide the diameter to get the radius then use the same equation.
Answer:
Q10 is 13.64 cm3
Q 11 is 221 cm3
Step-by-step explanation:
volume is cross sectional area times height for Q 10
volume is length times width times height for Q 11
The value of a would be 3.5, as a=1 when b=10 means that a is worth 1/10 of b's value.
I think this might help but sorry if it does not but I hope it does :) :D - https://learnzillion.com/lesson_plans/5701-writing-an-explicit-formula-for-the-graph-of-an-exponential-relationship/