Question

Ethan is proving the Exterior Angle Theorem, which states that the measure of an exterior angle of a triangle is equal to the sum of the measures of the two remote interior angles.

Given: Triangle ABC on line segment AD

Prove: m∠ A + m∠ B = m∠ BCD

https://learning.k12.com/content/enforced/437405-COF_ID125380/G-CO.C.10%20Q1.JPG?_&d2lSessionVal=FThQW1vA7Rx1GoKV8yqJ49s9v

https://learning.k12.com/content/enforced/437405-COF_ID125380/G-CO.C.10%20Q1.1.JPG?_&d2lSessionVal=FThQW1vA7Rx1GoKV8yqJ49s9v

What statement should Ethan add at Step 5 to complete the proof?
A. m∠ BCA+ m∠BCD = 90°

B. m∠ BCA= m∠BCD

C. m∠ BCA+ m∠BCD = 180°

D. m∠ BCA< m∠BCD

Answer 1

@563blackghost

Answer 2

Can't view the photos I dun have an account. You're gonna need to screenshot >.<

Answer 3

First, which do you think is the answer?

Answer 4

B or D

Answer 5

Not quite.

In step 4 of the proof you see that you state that `angle BCA and angle BCD are supplementary`.This means that the two angles `create a 180 degree` angle.

So by `definition of a supplementary angles`, `angle BCA + angle BCD = 180`.

Answer 6

A. In step 1, she compares the distances between the wrong pairs of points.


B. In step 2, she incorrectly calculates the distance between (3, 1) and(3, –4) .


C. In step 5, she simplifies incorrectly.


D. In step 4, she makes a sign error.