Question 164631
isosceles means that the two base angles are equal as are the sides opposite the angles


LW=TW  __  7X+21=4X+21  __  subtracting 4x+21  __  3X=0  __  X=0


LW=TW=21


there are 180º in a triangle  __  the vertex angle is 90º, so the sum of the two base angles is also 90º
__ so each bse angle equals 45º


by Pythagoras  __  LT^2=LW^2+TW^2  __  LT^2=2(21^2) __ LT=21*sqrt(2)