1:equilateral
2:isosceles
3:scalene
4:right
5:acute
6:obtuse
the answer to your question is 13 mm
The CN Tower is 553.33 m (1,815.4 ft) tall from its antenna spire. Meanwhile, the Eiffel Tower only measures 324.00 m (1,063 ft) from its antenna spire.
If the line is perpendicular, then as a rule the gradient of the perpendicular line will be the negative inverse of the gradient of the line given.
Therefore the gradient of the perpendicular line would be 1/2
so now just substitute in the equation of a line (y=mx+c) where y and x are given by -3 and 9, and your new m=1/2
Hope this helps