It is clear that
That should do it.
The attached image shows an isosceles trapezoid ABCD and AB is parallel to DC with angle BDC measuring 25 and BCA measuring 35. What is the measure of angle DBC?
I know the answer is 95 but I don't know how to justify (what do I need to show or prove??)
Right, the BASE angles are congruent big angle D and big angle C, but how do you justify that the others of the triangle are? How do we know that that triangle is isosceles?
How do you justify that ADC = BCD = 60?? I just dont see it
Check again, they arent congruent that way, how do you know that BDA is 35 and not 95, how do you find it?? I know all the properties of the isosc trap, I'm struggling proving that it is 95 guys.. The vertices dont match the angles that should be congruent either..