How many of the numbers from 10 through 98 have the sum of their digits equal to a perfect square?

In triangle △abc, ∠abc=90°, bh is an altitude. find the missing lengths. ab=9, and ac=12, find hc.

Line gh passes through points (2, 5) and (6, 9). which equation represents line gh? y = x + 3 y = x – 3 y = 3x + 3 y = 3x – 3

If cos(2x) = tan^2(y), show that cos(2y) = tan^2(x).