Sum of the radius of the base and height of a cylinder is 21 cm and the curved surface area of the cylinder is 616 sq. cm, find the total surface area of the cylinder.

925.04cm²

Step-by-step explanation:

Curved surface area of a cylinder = 2πrh

r is the radius

h is the height

If the sum of the radius of the base and height of the cylinder is 21 cm, then;

r + h = 21

r = 21-h 1

Recall:

CSA =  2πrh

616 = 2πrh 2

Substitute equation 1 into 2;

616 = 2π(21-h)h

616 = 2π(21h-h²)

616 = 42(3.14)h - 2(3.14)h²

616 = 131.88h - 6.28h²

98.09 = 21h - h²

h²-21h+98.09 = 0

h = 21±√21²-4(98.09)/2

h = 21±√441-392.36/2

h = 21±√48.64/2

h = 21±6/97/2

h = 21+6.97/2 and 21-6.97/2

h = 27.97/2 and 14.03/2

h = 13.985 and 7.015

Since r = 21-h

r = 21 - 13.985

Using r = 7.015

The total surface area = 2πrh + 2πr²

The total surface area = 616 + 2(3.14)7.015²

The total surface area = 616 + 309.04

The total surface area = 925.04

Hence the total surface area of the cylinder is 925.04cm²

there are 70 more legs than eyes at the dog show (196 – 126 = 70). dogs have two more legs than eyes, and humans have the same number of legs as eyes. thus 70 is twice the number of dogs at the show, so the number of dogs is half of 70, which is 35. to get the number of humans, subtract 35 from 63: 63 – 35 = 28.

step-by-step explanation: