The area of a trapezoid is one-half the sum of the lengths of the parallel sides multiplied by the height:

a = ½(b + d)(h)
a = ½(4 + 7)(4)
a = ½(11)(4)
a = ½(44) = \( \frac{44}{2} \)
a = 22

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).

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.

4a - 2a = 2a

The first step to solve a quadratic expression that's not set to zero is to solve the equation so that it is set to zero:

c² - 12c + 13 = -2c + 4
c² - 12c + 13 - 4 = -2c
c² - 12c + 2c + 9 = 0
c² - 10c + 9 = 0

Next, factor the quadratic equation:

c² - 10c + 9 = 0
(c - 1)(c - 9) = 0

For this expression to be true, the left side of the expression must equal zero. Therefore, either (c - 1) or (c - 9) must equal zero:

If (c - 1) = 0, c must equal 1
If (c - 9) = 0, c must equal 9

So the solution is that c = 1 or 9

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.