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An angle is 18° more than twice its complement. Find the angle.

Class 7Lines and AnglesLines and Angles
  • A24°
  • B126°
  • C66°
  • D54°

Step-by-Step Solution

Let the angle be , so its complement is . Then → → → °. Check: complement = 24°, and . Trap: 126° is the answer you get by using the SUPPLEMENT by mistake gives ); 24° is the complement, not the angle.
Answer: C) 66°

Key idea: Solving 'find the angle' problems

Most Class-7 angle problems give you one or two angle measures and ask you to find an unknown one. The recipe:

1. Identify the relationship: vertically opposite? linear pair? corresponding? alternate?
2. Write an equation: equal-to or sum-to-180.
3. Solve for the unknown.
4. Mark it back on the diagram and sanity-check (acute should look acute, obtuse should look obtuse).

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