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To construct a triangle similar in idea to ASA, a student is given base BC = 6 cm, angle B = 60° and angle A = 40 deg (an angle NOT on the base).
What is the first thing she should compute before constructing?

Class 9Constructions of TrianglesGeometry
  • Aangle C = 80°, then use base angles
  • Bside AB directly
  • Cthe perimeter
  • Dthe area

Step-by-Step Solution

Since angle A is given but not at the base, find angle C = 180 - 60 - 40 = 80°. Now both base angles (B = 60, C = 80) are known and the standard ASA construction can proceed.
Answer: A) angle C = 80°, then use base angles

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