Question

WILL GIVE BRAINLIEST! LOTS OF POINTS! MULTIPLE CHOICE Triangle ABC is a right triangle. Point D is the midpoint of side AB, and point E is the midpoint of side AC. The measure of ∠ADE is 47°. The proof, with a missing reason, proves that the measure of ∠ECB is 43°. Statement Reason m∠ADE = 47° Given m∠DAE = 90° Definition of a right angle m∠AED = 43° ? segment DE joins the midpoints of segment AB and segment AC Given segment DE is parallel to segment BC Midsegment of a Triangle Theorem ∠ECB ≅ ∠AED Corresponding angles are congruent m∠ECB = 43° Substitution property Which theorem can be used to fill in the missing reason? A. Concurrency of Medians Theorem B. Isosceles Triangle Theorem C. Triangle Inequality Theorem D. Triangle Sum Theorem

Answer 1

Answer:

Triangle Sum Theorem

Step-by-step explanation:

I believe it is that since we are given two angles, D is 47 and A is 90. Using the Triangle Sum Theorem, we know that a triangle's angles equals to 180 degrees so, 90+47=137, then 180-137=43.

Hope this helps!!! PLZ MARK BRAINLIEST!!!

Answer 2

Answer: D) Triangle Sum Theorem