The length of the base of a triangle is equal to the perimeter of a square whose diagonal is 7√2 cm and the corresponding height of the triangle is equal to the length of a side of the square whose area is 169 sq cm. The area (in sq cm) of the triangle is:
- AOption (a)
152
- BOption (b)
182
- COption (c)
156
- DOption (d)
130
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Correct answer
182
Why this answer is correct
Shortcut Trick
Base of triangle = 4 × (Diagonal of square / √2) = 4 × 7 = 28 cm.
Height of triangle = √(Area of square) = √169 = 13 cm.
Area of triangle = 1/2 × Base × Height = 1/2 × 28 × 13 = 182 sq cm.
∴ The correct answer is 182 sq cm.
Alternate Method
Given:
Diagonal of Square1 = 7√2 cm
Area of Square2 = 169 sq cm
Formula Used:
Side of square = Diagonal / √2
Perimeter of square = 4 × Side
Area of square = (Side)2
Area of triangle = (1/2) × base × height
⇒ Side of Square1 = 7√2 / √2 = 7 cm
⇒ Perimeter of Square1 = 4 × 7 = 28 cm
⇒ Base (b) of triangle = 28 cm
⇒ Side of Square2 = √169 = 13 cm
⇒ Height (h) of triangle = 13 cm
⇒ Area of triangle = (1/2) × 28 × 13
⇒ Area = 14 × 13 = 182 sq cm
∴ The correct answer is 182 sq cm.
Additional Information
Square Properties
Relationship between side (a) and diagonal (d): d = a√2. Area = a2 = d2/2.
Area of Triangle (Heron's Formula)
For a triangle with sides a, b, and c: Area = √[s(s−a)(s−b)(s−c)], where semi-perimeter s = (a + b + c)/2.
Equilateral Triangle
Area of an equilateral triangle with side 'a' is (√3 / 4) × a2 and height is (√3 / 2) × a.