Answer:
using the pythagoras theorem the answer is a=3
Step-by-step explanation:
basically in a right angled triangle a² + b² equals c². in this equation c is the number on the hypotenuse (the line opposite the right angle)
and 4 could be a or b it doesnt make a difference so I'll call it b.
because we have c² and b² we work backwards like this:


because 9 is a², we must find the square root to find <em>a</em>

so a equals 3
x^3=54 (Subtract 3 from both sides)
x = 3rd power cube root of 54 (Cube root both sides)
27 = 3^3 (3x3x3) therefore
x = (3) (3rd power cube root of 2)
M(x, y) = ((x1 + x2)/2, (y1 + y2)/2) = ((-2 + 6)/2, (5 - 9)/2) = (4/2, -4/2) = (2, -2)