A trapezoid is a 4-sided polygon which has 2 parallel sides.
Write an expression that represents the
perimeter of a trapezoid whose sides have
length a, b, c and d.

Use this expression to find the perimeter of
the trapezoid when a= 12. b
16. c = 16.
and d = 20.

Waves are used in many practical applications to support work, entertainment, and health. one example is the use of ultrasound imaging to safely track the development of a growing fetus. what is a specific example of a practical application of waves in medicine, entertainment, safety, or other fields? provide a brief explanation of how the properties of waves are useful to that application.