Triangle ABC is isosceles, equal angles at B and C = 80.Code:A E D C B
D is on AC, such that CD = BC.
E is on AB, such that angle BCE = 60.
Find size of angle DEC. No trigonometry allowed! Have fun.
Nice. I like this solution (# means angle) :
Triangle BCE: it is given that #ABC = 80 and #BCE = 60; then #BEC = 40
Triangle CDF: this triangle being equilateral, then #CFD = 60;
since #BFC = 80, this leaves #DFE = 180-80-60 = 40
Triangle DEF: #EDF = #DEF, so #CED + 40 = 70, hence #CED = 30