Please help :) 20 pts

What are the coordinates of the midpoint of ab? ,1/2) /2,-1) ,-3/2) /2,-2)

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.

What is the correct answer? urgent you