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(5 + 2)(4)
a = ½(7)(4)
a = ½(28) = \( \frac{28}{2} \)
a = 14

A rectangle is a parallelogram containing four right angles. Opposite sides (a = c, b = d) are equal and the perimeter is the sum of the lengths of all sides (a + b + c + d) or, comonly, 2 x length x width. The area of a rectangle is length x width. A square is a rectangle with four equal length sides. The perimeter of a square is 4 x length of one side (4s) and the area is the length of one side squared (s²).

You need to find the value of c so solve the first equation in terms of z:

-7c + z = 1
z = 1 + 7c

then substitute the result (1 - -7c) into the second equation:

-4c + 7(1 + 7c) = 8
-4c + (7 x 1) + (7 x 7c) = 8
-4c + 7 + 49c = 8
-4c + 49c = 8 - 7
45c = 1
c = \( \frac{1}{45} \)
c = \(\frac{1}{45}\)

The formula for area is πr². Radius is circle \( \frac{diameter}{2} \):

r = \( \frac{d}{2} \)
r = \( \frac{4}{2} \)
r = 2
a = πr²
a = π(2²)
a = 4π

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).