1. Determine the measure of the unknown angles indicated by letters. Justify your answers with the properties or theorems you used

hello,

Step-by-step explanation:

a)

In an isocele triangle, base's angles have the measure:

42+2a=180

2a=180-42

a=69(°)

b)

in a triangle, an external angle has for measure the sum of the angles not adjacents.

55+b=132

b=77 (°)

c)

in a quadrilater the sum of the (interior) angles is 2*180=360 degrees.

90+90+68+c=360

c=360-90-90-68

c=112 (°)

answer: all the values are within because it has a pattern that repeats from -6 to 4.

good luck!

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step-by-step explanation: