Finding angles in a trapezoid

Finding angles in a trapezoid
  • Currently 3.0/5 Stars.
6213 views, 1 rating - 00:04:40
Part of video series Solving for Angle Measures
Taught by mrbrianmclogan
I show how to solve math problems online during live instruction in class. This is my way of providing free tutoring for the students in my class and for students anywhere in the world. Every video is a short clip that shows exactly how to solve math problems step by step. The problems are done in real time and in front of a regular classroom. These videos are intended to help you learn how to solve math problems, review how to solve a math problems, study for a test, or finish your homework. I post all of my videos on YouTube, but if you are looking for other ways to interact with me and my videos you can follow me on the following pages through My Blog, Twitter, or Facebook.
At 20 seconds, the teacher says that the expressions 3y + 40 and 3x - 70 are equal, but actually they are supplementary, so (3y + 40) + (3x - 70) = 180. Again at 2:35, he says that 3y + 40 = 110, but because the angle are supplementary, you should have 3y + 40 + 110 = 180.
Finding the values of variables to find angles in a trapezoid by using alternate interior and corresponding angle theorems.
  • How do you find the angles in a trapezoid?
  • If 3 angles in a trapezoid are 120, x, and 3y + 40, and the the angles 3y + 40 and 3x - 70 are supplementary, what do x and y equal?
  • Why are the two angles on the side of a trapezoid supplementary?
  • How can you solve for x and y in a trapezoid when the angles are variable expressions?
This lesson shows how to solve a geometry problem for x and y when you are given a trapezoid with some angle measures given as variable expressions. The method used to solve for x and y is to use the expressions and your knowledge of trapezoids to solve for the unknown variables and finally the angle measures. All steps are explained.
  • Currently 3.0/5 Stars.
Reviewed by MathVids Staff on January 15, 2012.
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