Answer:
Step-by-step explanation:
In rectangle, the diagonals are equal bisect each other.
⇒ OA = OB
⇒ΔAOB is an isosceles triangle.
In ΔAOB,
x + x + 120 = 180°
2x + 120 = 180
2x = 180 -120
2x = 60
x = 30°
In ΔABD
∠A + ∠ABD ∠BDA = 180
90 + 30 + ∠BDA = 180
∠BDA = 180 - 90 -30 = 60°
ΔABD is 30 - 60 - 90 triangle.
The ratio of sides of 30-60-90 triangle is x : x√3 : 2x
x →shortest leg which is opposite ot 30°
∵ x = AD = 20
x√3 → longest leg which is opposite to 60°
x√3 ( AB) = 20*1.732
AB = 34.64
Area of rectangle = length * width
= 34.64 *20
= 692.8
≈ 693 square units
