Posted by Beatrice on .
the diagram below shoes a pennant in the shape of an isosceles triangle. the equal sides each measure 13, the altitude is x+7 and the base is 2x.

geometry 
Steve,
Draw the figure
x^2 + (x+7)^2 = 13^2
x^2 + x^2 + 14x + 49 = 169
x^2 + 7x  60 = 0
(x+12)(x5) = 0
x = 5
sides are 13,13,10
altitude is 12, making the halftriangle a 5,12,13 triangle.