1. You need to multiply the denominator by something that will make the content of the radical be a square—so that when you take the square root, you get something rational. Easiest and best is to multiply by √6. Of course, you must multiply the numerator by the same thing. Then simplify.
2. Identify the squares under the radical and remove them.
Answer:
90π units²
Step-by-step explanation:
(refer to attached)
Total Surface are off a right cylinder = area of its ends + area of curved surface
Given radius, r = 3 units and height, h = 12 units
Area of 2 ends,
= Area of 2 circles
= 2 x πr²
= 2π (3²)
= 2π (9)
=18π units²
Area of curved surface,
= 2πrh
= 2π(3)(12)
= 72π units²
Hence,
Surface area = 18π + 72π = 90π units²
