text: how do u find the perpendicular bisector of a triangle?how do u find the altitude of a triangle?   there is no such thing as the perpendicular bisector of a triangle. you can, however, find the perpendicular bisector of any of the three sides of the triangle.   suppose you have a triangle called abc and you wish to find the perpendicular bisector of the side ab. simply put the point of a compass at point a and open up the compass so that the pencil end is at point b. then draw a circle. now put the point of the compass on point b and the pencil end on point a and draw another circle. the two circles will intersect at two points which you might name e and f. now draw a line through e and f and passing through ab. this line will be the perpendicular bisector of ab.  every triangle has three altitudes. in the triangle abc, the line drawn from c perpendicular to the side ab is an altitude, so is the line drawn from b perpedicular to the line ac, and so is the line drawn from a perpendicular to the line bc.  the area of a triangle = 1/2 base times altitude. so if you know the area (a) and the base (b) then altitude = 2a/b.  hope this gives you the info you were looking for.