Question

What’s the answer for m

Answer 1

Answer:

$m\angle D=35.5^o$

Step-by-step explanation:

we know that

An isosceles triangle has two equal sides and two equal interior angles

In this problem

Triangle CDE is an isosceles triangle

because

EC ≅ DE

therefore

$m\angle C=m\angle D$ ----> equation A

Remember that

The sum of the interior angles in any triangle must be equal to 180 degrees

so

$m\angle C+m\angle D+m\angle E=180^o$ ----> equation B

$m\angle E=109^o$ ---> equation C

substitute equation A and equation C in equation B

$m\angle D+m\angle D+109^o=180^o$

$2m\angle D=180^o-109^o$

$m\angle D=35.5^o$