An isosceles triangle has two sides of equal length. An equilateral triangle has three sides of equal length. In a right triangle, two sides meet at a right angle.

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.

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

sa = 2πr² + 2πrh
sa = 2π(5²) + 2π(5 x 5)
sa = 2π(25) + 2π(25)
sa = (2 x 25)π + (2 x 25)π
sa = 50π + 50π
sa = 100π

To solve this equation, repeatedly do the same thing to both sides of the equation until the variable is isolated on one side of the equal sign and the answer on the other.

7b - 2 = -1 - 9b
7b = -1 - 9b + 2
7b + 9b = -1 + 2
16b = 1
b = \( \frac{1}{16} \)
b = \(\frac{1}{16}\)

The first step to solve a quadratic equation that's set to zero is to factor the quadratic equation:

c² + 15c + 54 = 0
(c + 6)(c + 9) = 0

For this expression to be true, the left side of the expression must equal zero. Therefore, either (c + 6) or (c + 9) must equal zero:

If (c + 6) = 0, c must equal -6
If (c + 9) = 0, c must equal -9

So the solution is that c = -6 or -9