A tetrahedron.
a shape or figure with no bent or curvy lines only striaght lines and has three sides which the sum of the angles must equal 180 degress
A figure with 8 equal sides.
Regular :)
It is a geometric figure with eight equal sides.
We need more information ! Any regular polygon has equal angles !
The figure is a pyramid and the base is a square.
There is a contradiction in your question. If the base has four equal sides then is it a square so not all the faces are Triangles. However if the base is a square and the rest of the faces are triangles then your object is a "Square-based Pyramid"
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The answer is a pyramid.
A pyramid.
octagonal pyramid
A pyramid with a triangular base. The faces are 4 equilateral triangles.