1) We know, Circumference = 2πr
If radius is tripled, then, C' = 2π(3r) = 6πr = 3 * 2πr = 3 * C
So, Circumference will also get increased to it's triple value
2) We know, Area = πr²
If radius is doubled, π(2r)² = 4π²
So, Area will increase 4 times to it's intial value
Hope this helps!
