To find the missing angle in any triangle, we use this rule:
The three interior angles of a triangle always add up to 180°.
So for each problem, we’ll:
- Add the two known angles.
- Subtract that sum from 180° to get the missing angle.
Let’s go one by one:
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1) Triangle TUV: ∠T = 37°, ∠V = 63° → Find ∠U
37 + 63 = 100
180 - 100 =
80°
→ m∠U = 80°
---
2) Triangle ABC: Right angle at C (90°), ∠A = 46° → Find ∠B
90 + 46 = 136
180 - 136 =
44°
→ m∠B = 44°
---
3) Triangle PQR: ∠P = 51°, ∠R = 36° → Find ∠Q
51 + 36 = 87
180 - 87 =
93°
→ m∠Q = 93°
---
4) Triangle EFG: ∠G = 86°, ∠E = 47° → Find ∠F
86 + 47 = 133
180 - 133 =
47°
→ m∠F = 47°
---
5) Triangle XYZ: ∠Z = 118°, ∠X = 33° → Find ∠Y
118 + 33 = 151
180 - 151 =
29°
→ m∠Y = 29°
---
6) Triangle WUV: ∠W = 42°, ∠U = 64° → Find ∠V
42 + 64 = 106
180 - 106 =
74°
→ m∠V = 74°
---
7) Triangle LMK: ∠L = 60°, ∠M = 60° → Find ∠K
60 + 60 = 120
180 - 120 =
60°
→ m∠K = 60°
*(This is an equilateral triangle — all angles equal!)*
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8) Triangle SUT: ∠S = 35°, ∠T = 35° → Find ∠U
35 + 35 = 70
180 - 70 =
110°
→ m∠U = 110°
---
9) Triangle CDE: ∠E = 53°, ∠D = 77° → Find ∠C
53 + 77 = 130
180 - 130 =
50°
→ m∠C = 50°
---
Final Answer:
1) 80°
2) 44°
3) 93°
4) 47°
5) 29°
6) 74°
7) 60°
8) 110°
9) 50°
Parent Tip: Review the logic above to help your child master the concept of triangle angle sum worksheet.
