A cylinder is a solid figure with straight parallel sides and a circular or oval cross section with a radius (r) and a height (h). The volume of a cylinder is π r²h and the surface area is 2(π r²) + 2π rh.

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 -10 as well and sum (Inside, Outside) to equal 3. For this problem, those two numbers are -2 and 5. Then, plug these into a set of binomials using the square root of the First variable (y²):

y² + 3y - 10
y² + (-2 + 5)y + (-2 x 5)
(y - 2)(y + 5)

The formula for area is πr²:

a = πr²
a = π(4²)
a = 16π

A right angle measures 90 degrees and is the intersection of two perpendicular lines. In diagrams, a right angle is indicated by a small box completing a square with the perpendicular lines.

Perimeter is equal to the sum of the four sides:

p = a + b + c + d
p = 4 + 6 + 9 + 2
p = 21