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First Year maths · S.7 · Angles and triangles

Base angles of an isosceles triangle

In an isosceles triangle the two base angles are equal. All three angles add to 180 degrees.

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  1. An isosceles triangle has an apex angle of 140°. How many degrees is each base angle?

    Answer: 20

  2. An isosceles triangle has an apex angle of 98°. How many degrees is each base angle?

    Answer: 41

  3. An isosceles triangle has an apex angle of 46°. How many degrees is each base angle?

    Answer: 67

Tip: In an isosceles triangle the two base angles are equal. All three angles add to 180 degrees.

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