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I basically just have to find the angles but I also want to understand so if you could explain?

I basically just have to find the angles but I also want to understand so if you could-example-1

1 Answer

7 votes

9514 1404 393

Answer:

c = 108°

d = 106°

Explanation:

There are 2 basic rules involved here. From them, a number of others can be derived in order to simplify some calculations.

  1. angles forming a linear pair are supplementary (total 180°)
  2. interior angles of a triangle total 180°

The derived relations we can use in this problem are ...

  • vertical angles are congruent
  • an exterior angle of a triangle is equal to the sum of the opposite interior angles

__

c

The vertical angle to 78° is one of two remote interior angles with respect to exterior angle c. The other is the one marked 30°. That means ...

c = 78° +30* = 108°

__

d

Angles d and 30° are two of the three angles in the largest triangle. The third is the vertical angle to 44°, so it is 44°. The sum of angles in that triangle is 180°:

d + 30° +44° = 180°

d = 180° -74° = 106°

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