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).

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 trapezoid is a quadrilateral with one set of parallel sides.

You need to find the value of a so solve the first equation in terms of x:

-6a + x = 5
x = 5 + 6a

then substitute the result (5 - -6a) into the second equation:

3a + 4(5 + 6a) = -9
3a + (4 x 5) + (4 x 6a) = -9
3a + 20 + 24a = -9
3a + 24a = -9 - 20
27a = -29
a = \( \frac{-29}{27} \)
a = -1\(\frac{2}{27}\)

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).