From the figure, ABCD is a parallelogram with base AB = 35 cm and corresponding altitude DL.
The adjacent side of the parallelogram AD = 20 cm.
It is given that the area of the parallelogram ABCD = 560 cm2
Now, Area of the parallelogram = Base x Height
560 cm2 = AB x DL
560 cm2 = 35 cm x DL
DL = 560/235
= 16 cm
Again by Pythagoras theorem, we have, (AD)2 = (AL)2 + (DL)2
(20)2= (AL)2 + (16)2
(AL)2= (20)2– (16)2
= 400 – 256
= 144
(AL)2 = (12)2
AL = 12 cm
From the figure, AB = AL + LB
35 = 12 + LB
LB = 35 – 12 = 23 cm
Hence, length of LB is 23 cm.
