Question

please explain the above question....​

Answer 1

Answer:

B) (a+b)

explaination :

given, ABCD is a trapezium in which AB || CD,

angle ADC = 2 angle ABC,

AD = a cm and CD = b cm

Since the adjacent sides of trapezium are supplementry,

ADC + ABC= 180°

3ABC = 180°

Also ABC =60°, BAD=60°

and ADC=120°, CBA=120°

(refer given attachment for diagram)

Draw a perpendicular DM bisecting AB, then triangle ADM is formed with DAM =60°.

cos60 = 1/2= AM/AD

Hence AM/a=1/2 and AM=a/2

Similarly the other side perpendicular CN is drawn and cos60 BN = a/2

The remaining part is same as b.

AB = a/2 + a/2 + b = (a+b)