21 because a triangle is always going to equal 180 so add those then subtract and it’s 21
Answer:
m∠GDE
alternate interior angles
There all 9's therefore they all have the same value
The hypotenuse of the triangle is given by:

Substituting values:

Clearing CB we have:

Then, the perimeter of the triangle is:

Substituting values:
Answer: the perimeter of triangle BRC in units is: D.6 + 2√5
This answer to this question is 1150 km