First blank: Definition of a right triangle.
A right triangle is a triangle that has exactly one right angle.
Second blank: sin M = h/p, and sin P = h/m
The ratio for sin. is opposite over hypotenuse.
Third blank: Substitution property of equality
In this step, we are substituting the value of h into the first equation.
Fourth blank: Division property of equality
We are dividing both sides of the equation by the same divisor.
Hope this helps!