If m<1=53 degrees, what is m<3. David states that DEF is an isosceles triangle. Is he correct. Explain

Answer:
Angle 3 is 143 degrees
He is not correct. The triangle is not isosceles.
========================================================
Part 1
Angle 1 and angle 2 are complementary angles. They add to 90 degrees. So
(angle1) + (angle2) = 90
53 + (angle2) = 90
angle2 = 90 - 53
angle2 = 37 degrees
Subtract this result from 180 to get the value of angle 3. This is because angle 2 and angle 3 are supplementary angles. They are a linear pair (aka the angles form a straight line)
angle3 = 180 - (angle2)
angle3 = 180 - 37
angle3 = 143 degrees
note: you can add the remote interior angles at D and E to get 90+53 = 143 and you get the same answer. This is using the exterior angle theorem.
-----------
Part 2
In order for the triangle to be isosceles, the two acute angles (angle 1, angle 2) must be congruent. Call them x for now. They must also add to 90, so x+x = 90 leads to 2x = 90 and solves to x = 45. Both angle 1 and angle 2 must be 45 degrees. However, angle 1 is 53 degrees and angle 2 is 37 degrees. So that is why David's statement is not correct.
David states that DEF is an isosceles triangle.
David's statement is not correct.
Part 1
∠1 and angle ∠2 are complementary angles. They add to 90°.
So, ∠1 + ∠2 = 90°
53° +∠2 = 90°
∠2 = 90° - 53°
∠2 = 37°
Subtract this result from 180° to get the value of ∠3. This is because ∠2 and ∠3 are supplementary angles. They are a linear pair (the angles form a straight line).
∠3 = 180° - ∠2
∠3 = 180° - 37°
∠3 = 143°
note: you can add the remote interior angles at D and E to get 90+53 = 143 and you get the same answer. This is using the exterior angle theorem.
Part 2
In order for the triangle to be isosceles, the two acute angles (∠1, ∠2) must be congruent. Call them x for now. They must also add to 90°, so x+x = 90° leads to 2x = 90° and solves to x = 45°. Both angle 1 and angle 2 must be 45 degrees. However, angle 1 is 53 degrees and angle 2 is 37 degrees. So that is why David's statement is not correct.
Therefore, David's statement is not correct.
For more information:
https://brainly.com/question/3884354