30 because the angles of the triangle should be 180. Since we know one is 90 the other is 60 so 180-(90+60)=30
It is convenient to do part b first, then use that result to do part a.
b. For some pair of points (x1, y1) and (x2, y2), you want to find a point (a, b) such that (a, b) - (x1, y1) = (x2, y2) - (a, b). That is, the differences of coordinates from one end to the center are the same as the differences from the center to the other end.
Adding (a, b) to the above equation gives
2(a, b) - (x1, y1) = (x2, y2)
Adding (x1, y1) then gives
2(a, b) = (x1, y1) + (x2, y2)
Finally, dividing by 2 gives a formula for (a, b):
(a, b) = ((x1, y1) + (x2, y2))/2
The midpoint is the average of the end points.
a. Using the result from part b, the midpoint is
midpoint = ((2, 3) + (6, 7))/2 = (8, 10)/2
midpoint = (4, 5)
Lets get the negative reciprocal of the slope so we get

Now the equation that is perpendicular is

Lets solve for b by plugging in the point (x,y)=(6,1)

Now plug that into the equation. So the equation of the line that is perpendicular and
passes through the point (6, 1) is