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

To multiply binomials, use the FOIL method. FOIL stands for First, Outside, Inside, Last and refers to the position of each term in the parentheses:

(y - 7)(y + 8)
(y x y) + (y x 8) + (-7 x y) + (-7 x 8)
y² + 8y - 7y - 56
y² + y - 56

An exterior angle of a triangle is equal to the sum of the two interior angles that are opposite:

d° = b° + c°

To find angle c, remember that the sum of the interior angles of a triangle is 180°:

180° = a° + b° + c°
c° = 180° - a° - b°
c° = 180° - 36° - 34° = 110°

So, d° = 34° + 110° = 144°

A shortcut to get this answer is to remember that angles around a line add up to 180°:

a° + d° = 180°
d° = 180° - a°
d° = 180° - 36° = 144°

To multiply monomials, multiply the coefficients (the numbers that come before the variables) of each term, add the exponents of like variables, and multiply the different variables together.

(8a)(3ab) + (9a²)(9b)
(8 x 3)(a x a x b) + (9 x 9)(a² x b)
(24)(a¹⁺¹ x b) + (81)(a²b)
24a²b + 81a²b
105a²b

A rhombus is a parallelogram with four equal-length sides. A square is a rectangle with four equal-length sides.