Maths-
General
Easy
Question
In the figure, if AB = AC, and AE = AD, then x is equal to
- 15º
- 10º
- 12½
- 7½
Hint:
assume the base angles to be any variable and apply the property that sum of interior angles of a triangle = 180 degree
The correct answer is: 15º
15
Let angle B= C =y
A= 180 – 2y
Angle DAC = 180-2y-30=150-2y
ADE= DEA
2<ADE =180 – (150-2y)=2y+30
<ADE= y+15
<ADC = <ABD + <DAB( exterior angle = sum of interior opposite angles)
15+y +x= 30 + y
X=15 degree
exterior angle = sum of interior opposite angles is a property of triangles
sum of interior angles of a triangle = 180 degree
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