Question

maths plzzzzz help ​

Answer 1

Given ABCD is a quadrilateral [Note: Not a Trapezium]

angle ADC = y

angle ABC = x

angle DEA = b

angle BCF = a

since we know that ,

Sum of angles on a Straight line is 180°

and Sum of angles in a Quadrilateral is 360°

then,

angle DAB = (180 - b)°    and     angle BCD = (180 - a)°

now in Quad. ABCD

angle ADC + angle ABC + angle DAB + angle BCD = 360°

putting the values ,

y + x + (180 - b) + (180 - a) = 360°

x + y - a - b + 360 = 360

x + y - a - b = 0

x + y = a + b

therefore , correct option is (A).

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I hope you understand.