Find the area of the isosceles trapezoid with lower base 18cm, legs 6cm and base angles 30 degrees

Answer 1

To have a triangle the sum of any two sides must be greater than the third side
6+6 is not greater than 18

Your triangle cannot exist.

Answer 2

The coordinates of the vertices of a polygon are R(-4, 3), S(-4, -7), T(5, -7), and V(5, 3). Find the area and determine whether it is a parallelogram, rectangle, or square.