- A33
- B60
- C27
- D30
Step-by-Step Solution
The two acute angles sum to 90°. Let smaller = , larger = → → °.
Answer: D) 30
In a right triangle, one acute angle is twice the other. Find the smaller acute angle in degrees.
Class 7The Triangle and its PropertiesTriangles
Key idea: Angle sum property
**The three interior angles of any triangle sum to 180°.**
This is true for every triangle — equilateral, isosceles, scalene, right, acute, or obtuse. Use it to find a missing angle when you know the other two: third angle = 180° − (first) − (second).
Special cases:
- Equilateral: all angles equal → each is 60°.
- Right triangle: one is 90°, so the other two sum to 90° (they are complementary).
This is true for every triangle — equilateral, isosceles, scalene, right, acute, or obtuse. Use it to find a missing angle when you know the other two: third angle = 180° − (first) − (second).
Special cases:
- Equilateral: all angles equal → each is 60°.
- Right triangle: one is 90°, so the other two sum to 90° (they are complementary).
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