Asked by Lindsay
In a quadrilateral ABCD, Angle A = 120 degrees, Angle B = 140 degrees.
The bisectors of the angles C and D meet at the point Y.
What is the size of the angle DYC?
The bisectors of the angles C and D meet at the point Y.
What is the size of the angle DYC?
Answers
Answered by
drwls
The sum of angles C and D must be 100 degrees, so that angles A, B, C and D add up to 360 degrees for the quadrilateral.
Half of the sum of 100 degrees (which is 50 degrees) must be the sum of the two bisected acute angles C and D. Two of those bisected angles form triangle DYC. That angle must therefore be 180-50 = 130 degrees at point Y.
It will be clearer if you draw yourself a picture. The angles C and D can be arbitratily drawn, but their sum has to be 100 degrees.
Half of the sum of 100 degrees (which is 50 degrees) must be the sum of the two bisected acute angles C and D. Two of those bisected angles form triangle DYC. That angle must therefore be 180-50 = 130 degrees at point Y.
It will be clearer if you draw yourself a picture. The angles C and D can be arbitratily drawn, but their sum has to be 100 degrees.
Answered by
Anonymous
bottom...he he he