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Triangles and Angles

Quantitative Aptitude · Maths Bookwise · Geometry & Mensuration

Useful for: SSC CGL

BOOK-GUIDED ORIGINAL SSC MATHS PRACTICE — Triangles and Angles

FOUNDATION

Interior angles of a triangle sum to 180°.

METHOD

Identify the quantities given, choose the exact relationship, calculate in the same unit, then check the answer against the question.

WORKED EXAMPLE 1

Two angles of a triangle are 65° and 31°. Find its third angle (degrees).

Angle sum = 180°. Third angle = 180−65−31=84°.

WORKED EXAMPLE 2

Two angles of a triangle are 53° and 72°. Find its third angle (degrees).

Angle sum = 180°. Third angle = 180−53−72=55°.

IMPORTANT EXCEPTION / COMMON TRAP

Do not confuse interior and exterior angles.

QUICK REVISION

Interior angles of a triangle sum to 180°.

SEE MORE: https://study.kundali-iq.com/ssc-maths/geometry/

For complete timed maths practice, use SSC CGL Test Series → New Maths 100 Mixed Sets or Chapter-wise sets. These are independent original questions, not copied previous-year questions.

Practice MCQs

  1. Two angles of a triangle are 65° and 31°. Find its third angle (degrees).

    1. 84
    2. 89
    3. 79
    4. 94

    Read chapter notes · Similar questions

    Show answer

    Answer: (a) 84. Angle sum = 180°. Third angle = 180−65−31=84°.

  2. Two angles of a triangle are 53° and 72°. Find its third angle (degrees).

    1. 61
    2. 52
    3. 58
    4. 55

    Read chapter notes · Similar questions

    Show answer

    Answer: (d) 55. Angle sum = 180°. Third angle = 180−53−72=55°.

  3. Two angles of a triangle are 70° and 50°. Find its third angle (degrees).

    1. 64
    2. 60
    3. 56
    4. 68

    Read chapter notes · Similar questions

    Show answer

    Answer: (b) 60. Angle sum = 180°. Third angle = 180−70−50=60°.

  4. Two angles of a triangle are 75° and 53°. Find its third angle (degrees).

    1. 49
    2. 58
    3. 52
    4. 55

    Read chapter notes · Similar questions

    Show answer

    Answer: (c) 52. Angle sum = 180°. Third angle = 180−75−53=52°.

  5. Two angles of a triangle are 52° and 63°. What is its third interior angle

    1. 55°
    2. 65°
    3. 75°
    4. 85°

    Read chapter notes · Similar questions

    Show answer

    Answer: (b) 65°. Interior angles sum to 180°, so third angle = 180° − 52° − 63° = 65°.

More topics in this chapter

Notes and questions are written by Kundali IQ for practice. They are not official papers; always check the latest official notification for the syllabus and pattern.