What is the best estimate of the mass of a pencil.

Identify a1 and r for the geometric sequence an= -256(-1/4) n-1

Cuántos triángulos forman un diamante

The pyraminx is a rubik's cube-type toy in the shape of a tetrahedron. the pyraminx shown below has edges 15\,\text{cm}15cm long and vertical height h=12.2\,\text{cm}h=12.2cm. the triangle drawn with dashed lines is a right triangle. what is the distance rr? round your answer to the nearest tenth.