Isosceles Triangle Base (A) Calculator

Your details

Pick which two values you know. The base A is computed from those inputs.
Length of each of the two equal sides of the isosceles triangle.
cm
The perpendicular height from the base to the apex (vertex).
cm
Base (A)
12cm

Length of the base of the isosceles triangle

Leg (B)10cm
Height (H)8cm
Perimeter32cm
Area48cm²
Base angle36.87deg
Vertex angle106.26deg
Inradius3cm
Circumradius8.3333cm

Base A = 12.0000 cm with vertex angle 106.26 deg

  • This is an obtuse isosceles (vertex angle greater than 90 deg).
  • The base (12.0000 cm) is longer than each leg (10.0000 cm), making the triangle wide and flat.
  • The perpendicular height is 8.0000 cm, giving an area of 48.0000 cm^2.

Next stepUse the perimeter, area, and angle results below to fully characterize your triangle. For design or construction work, verify that the height constraint H < B holds, since the height must always be less than the leg length.

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