If triangle ABC is congruent to triangle DEC, then all the lengths and angles in the one triangle are equal to their corresponding lengths and angles in the other triangle.
in the linear equation the greatest power of the variables is 1 for example:2X+4 this is a linearequationasthegreatestpowerofthevariableX is 1also by drawing it in a graph you will obtain a straight line
while in the quadratic equation the greatestpoweris2for instance:X^2+4X-3 this is a QuadraticequationbecausethegreatestpowerofthevariableX is 2also by drawing it on a graph you will obtain a parabola which is a curve "an upward curve or downward curve"