Which expression represents the combine donations made by them?

In triangle △abc, ∠abc=90°, bh is an altitude. find the missing lengths. ab=4 and bc=3, find ah, ch and bh.

Aregular hexagon rotates counterclockwise about its center. it turns through angles greater than 0° and less than or equal to 360°. at how many different angles will the hexagon map onto itself?

Simplify a7/a4 a) 1/a3 b)-a/a2 c)a4/a3 d)a3