4) Without actually adding how can you tell if the sum of two numbers will be zero? Give an example,​

An angle that measures between 90 and 180° is called a(,

The sum of five and a number n is at least 12

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.