A line segment is a portion of a line with a measurable length. The midpoint of a line segment is the point exactly halfway between the endpoints. The midpoint bisects (cuts in half) the line segment.

A triangle is a three-sided polygon. It has three interior angles that add up to 180° (a + b + c = 180°). An exterior angle of a triangle is equal to the sum of the two interior angles that are opposite (d = b + c). The perimeter of a triangle is equal to the sum of the lengths of its three sides, the height of a triangle is equal to the length from the base to the opposite vertex (angle) and the area equals one-half triangle base x height: a = ½ base x height.

The Pythagorean theorem defines the relationship between the side lengths of a right triangle. The length of the hypotenuse squared (c²) is equal to the sum of the two perpendicular sides squared (a² + b²): c² = a² + b² or, solved for c, \(c = \sqrt{a + b}\)

A trapezoid is a quadrilateral with one set of parallel sides.

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

-c + y = 7
y = 7 + c

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

c - 8(7 + c) = -2
c + (-8 x 7) + (-8 x c) = -2
c - 56 - 8c = -2
c - 8c = -2 + 56
-7c = 54
c = \( \frac{54}{-7} \)
c = -7\(\frac{5}{7}\)