The surface area of a cylinder is 2πr² + 2πrh:

sa = 2πr² + 2πrh
sa = 2π(7²) + 2π(7 x 8)
sa = 2π(49) + 2π(56)
sa = (2 x 49)π + (2 x 56)π
sa = 98π + 112π
sa = 210π

The area of a triangle is equal to ½ base x height:

a = ½bh
a = ½ x 8 x 1 = \( \frac{8}{2} \) = 4

A triangle is a three-sided polygon. It has three interior angles that add up to 180° (a + b + c = 180°). An exterior angle of a triangle is equal to the sum of the two interior angles that are opposite (d = b + c). The perimeter of a triangle is equal to the sum of the lengths of its three sides, the height of a triangle is equal to the length from the base to the opposite vertex (angle) and the area equals one-half triangle base x height: a = ½ base x height.

To factor a quadratic expression, apply the FOIL method (First, Outside, Inside, Last) in reverse. First, find the two Last terms that will multiply to produce 25 as well and sum (Inside, Outside) to equal 10. For this problem, those two numbers are 5 and 5. Then, plug these into a set of binomials using the square root of the First variable (y²):

y² + 10y + 25
y² + (5 + 5)y + (5 x 5)
(y + 5)(y + 5)

To combine like terms, add or subtract the coefficients (the numbers that come before the variables) of terms that have the same variable raised to the same exponent.

7a + 6a = 13a