To find the missing angle in each triangle, we use this rule:
The three angles inside any triangle always add up to 180 degrees.
So, if you know two angles, you can find the third by:
1. Adding the two known angles together.
2. Subtracting that sum from 180.
Let’s solve each one step by step.
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1) Triangle with angles 54° and 49°, find ∠D
Add: 54 + 49 = 103
Subtract from 180: 180 - 103 =
77
→ m∠D =
77°
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2) Right triangle (one angle is 90°), another is 36°, find ∠B
Add: 90 + 36 = 126
Subtract from 180: 180 - 126 =
54
→ m∠B =
54°
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3) Triangle with angles 50° and 38°, find ∠Q
Add: 50 + 38 = 88
Subtract from 180: 180 - 88 =
92
→ m∠Q =
92°
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4) Triangle with angles 60° and 40°, find ∠Z
Add: 60 + 40 = 100
Subtract from 180: 180 - 100 =
80
→ m∠Z =
80°
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5) Triangle with angles 114° and 27°, find ∠Y
Add: 114 + 27 = 141
Subtract from 180: 180 - 141 =
39
→ m∠Y =
39°
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6) Triangle with angles 52° and 48°, find ∠V
Add: 52 + 48 = 100
Subtract from 180: 180 - 100 =
80
→ m∠V =
80°
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7) Triangle with angles 104° and 32°, find ∠K
Add: 104 + 32 = 136
Subtract from 180: 180 - 136 =
44
→ m∠K =
44°
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8) Triangle with angles 55° and 30°, find ∠U
Add: 55 + 30 = 85
Subtract from 180: 180 - 85 =
95
→ m∠U =
95°
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9) Right triangle (one angle is 90°), another is 38°, find ∠E
Add: 90 + 38 = 128
Subtract from 180: 180 - 128 =
52
→ m∠E =
52°
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Final Answer:
1) 77°
2) 54°
3) 92°
4) 80°
5) 39°
6) 80°
7) 44°
8) 95°
9) 52°
Parent Tip: Review the logic above to help your child master the concept of interior exterior angles worksheet.
