Question

Exercise 1.8
A. For each triangle calculate the size of the unmarked angle.



1)60°
90°
2)45°
90°
3)65°
55°
​

Answer 1

Answer:

65 degree

Step-by-step explanation:

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Answer 2

Answer:

$sum \: of \: the \: interior \: angles \: of \: a \: triangle \: s \: 180 \\ here \: two \: angles \: are \: given \: a + b + c = 180 \\ 60 + 90 + c = 180 \\ 170 + c = 180 \\ c = 10 \\ \\ 2) \: a + b + c = 180 \\ 45 + 90 + c = 180 \\ 135 + c = 180 \\ c = 45 \\ \\ 3) x + y + z = 180 \\ x + 65 + 55 = 180 \\ x + 120 = 180 \\ x = 180 - 120 \\ x = 60$