A parallelogram is a quadrilateral with two sets of parallel sides. Opposite sides (a = c, b = d) and angles (red = red, blue = blue) are equal. The area of a parallelogram is base x height and the perimeter is the sum of the lengths of all sides (a + b + c + d).

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.

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.

6b - 1 = \( \frac{b}{-6} \)
-6 x (6b - 1) = b
(-6 x 6b) + (-6 x -1) = b
-36b + 6 = b
-36b + 6 - b = 0
-36b - b = -6
-37b = -6
b = \( \frac{-6}{-37} \)
b = \(\frac{6}{37}\)

The formula for circumference is circle diameter x π:

c = πd
c = 10π

The formula for area is πr²:

a = πr²
a = π(2²)
a = 4π