Find cos A in the following triangle A20 B21 C29

Name the quadrilaterals that have four equal sides.

The square root of 9x plus 7 plus the square rot of 2x equall to 7

Adolphin is swimming with her friend. the dolphin jumps to a height of 4.54.54, point, 5 meters above the surface of the water as her friend swims 9.89.89, point, 8 meters directly below her. what is the position of the dolphin's friend relative to the surface of the water? meters