Find the measure of each angle plz do 15 and 16

15) 55°

16) 90°

Step-by-step explanation:

15)

55° + 75° + x = 180°

x = 50°

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50° + 60° + x = 180°

x = 70°

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70° + 55° + ? = 180°

? = 55°

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16)

55° + 90° + x = 180°

x = 35°

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35° + x = 90°

x = 55°

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55° + 35° + ? = 180°

? = 90°

x² + 3x + 7 = 0       [ax² + bx + c]

a = 1

b = 3

c = 7

quadratic formula:

    (+/- is this ±)

plug in the numbers into the variables

your answer is a