Question

Figure PQRS represents the top view of a rectangular window. Find its area.

• A. 440 sq. ft
• B. 400 sq. ft
• C. 441 sq. ft
• D. 420 sq. ft

Answer 1

The correct option is D 420 sq. ft

We know,
Area of a rectangular window = Length x Breadth

Given: Breadth = 20 ft

Apply pythgoras theorem in triangle PQR to find the length of the rectangle,

$P{Q}^2+Q{R}^2=P{R}^2$ (By pythagoras theorem)
where,
QR = 20 ft
PR = 29 ft

$\left(P{Q}^2\right)+\left({20}^2\right)=\left({29}^2\right)$

$\left(P{Q}^2\right)=\left({29}^2\right)-\left({20}^2\right)$

$\left(P{Q}^2\right)=\left(841\right)-\left(400\right)$

$\left(P{Q}^2\right)=441$

⇒ Length (PQ) = <!--td {border: 1px solid #ccc;}br {mso-data-placement:same-cell;}--> 21 ft

$\text{Area of PQRS =}21\times 20$
$=420\text{sq. in}$