A circle is a figure in which each point around its perimeter is an equal distance from the center. The radius of a circle is the distance between the center and any point along its perimeter. A chord is a line segment that connects any two points along its perimeter. The diameter of a circle is the length of a chord that passes through the center of the circle and equals twice the circle's radius (2r).

The sum of the interior angles of a triangle is 180°:
180° = a° + b° + c°
c° = 180° - a° - b°
c° = 180° - 45° - 35° = 100°

The circumference of a circle is the distance around its perimeter and equals π (approx. 3.14159) x diameter: c = π d. The area of a circle is π x (radius)² : a = π r².

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

x² + 3x - 18 = 0
(x - 3)(x + 6) = 0

For this expression to be true, the left side of the expression must equal zero. Therefore, either (x - 3) or (x + 6) must equal zero:

If (x - 3) = 0, x must equal 3
If (x + 6) = 0, x must equal -6

So the solution is that x = 3 or -6

The volume of a cube is height x length x width:

v = h x l x w
v = 9 x 7 x 5
v = 315