a right cylinder has a radius of 3 and a height of 12. what is its surface area?
a. 457 pi units squared
b. 90 pi units squared
c. 108 pi units squared
d. 72 pi units squared

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

step-by-step explanation:

∆abc has the points a(1, 7), b(-2, 2), and c(4, 2) as its vertices. formed with the point d(1, 2) as its third vertex, then ∆abd is triangle.

dc=6 square root of 3 and ac is 12 square root 3

c and d

step-by-step explanation:

square root of 3/2 = 18/c

cross multiply to get 18*2=√3*c

36/√3 * √3/√3 = c

c= 36*√3/3

c=12√3