Question

A plot of land has been surveyed for a new housing development with borders AB, BC, DC, and DA. The plot of land is a right trapezoid with a height of 60 feet and an opposite leg length of 65 feet. If the measure of angle BCD is 61°, the measure of angle ABC is °. If the length of base AB is 80 feet, the length of DC is feet.

Answers are 119, and 105 on e2020

Answer 1

First one: 112.6 Second one: 105

Explanation:

Answer 2

m∠ABC = 119° and DC = 105 feet

Explanation:

For better understanding of the solution see the attached figure of the trapezium ABCD :

m∠BCD = 61°

By using the property, Sum of interior opposite angles in a trapezium is supplementary ⇒ m∠BCD + m∠ABC = 180°

⇒ m∠ABC = 180° - 61°

⇒ m∠ABC = 119°

Now, to find length of DC,

Draw a perpendicular BE on CD ⇒ CD = DE + EC

AB = DE

⇒ DE = 80 feet

In ΔBEC, By using Pythagoras theorem

EC² = BC² - BE²

⇒ EC² = 65² - 60²

⇒ EC = 25 feet

Hence, DC = 80 + 25

= 105 feet