The given park ABCD is in the shape of the square, i.e all teh four sides of the part are equal and the angle made by intersection of two side is 90 degree.
i.e.m AB = BC = CD = DA = 120m
and the angle A = Angle B = Angle C = Angle D = 90°
We need to find the length of the diagonal DB,
The side BCD makes a right angle at angle C
In triangle BCD;
BC = 120, CD = 120 for the side DB
Apply Pythagoras theorem;
In a right-angled triangle, the square of the hypotenuse side is equal to the sum of squares of the other two sides.
Hypotenuse² = Base ² + Perpendicular²
Substitute, hypotenuse, = DB, Base CD = 120, Perpendicular BC = 120
Hypotenuse² = Base ² + Perpendicular²
DB² = CD² + BC²
DB² = 120² + 120²
DB² = 14400 + 14400
DB² = 28800
DB = 169.70
Since, 169.70 ~ 170
Therefore, DB = 170m
The length of diagonal is 170m
Answer : B) 170m