Question

The approximate area of triangle having sides of length 2.4 cm, 5.8 cm and 6.8 cm is

• A. 4.25 cm${}^2$
• B. 8.25 cm${}^2$
• C. 7.50 cm${}^2$
• D. 6.75 cm${}^2$

Answer 1

The correct option is D 6.75 cm${}^2$

Let the sides of the triangle be a = 2.4 cm, b = 5.8 cm and c = 6.8 cm.
$\therefore$ Semi-perimeter of triangle, (s)
$=\frac{a+b+c}{2}$
$=\frac{2.4+5.8+6.8}{2}$
= 7.5 cm
$\therefore$ Area of triangle $=\sqrt{s(s-a)(s-b)(s-c)}$
$=\sqrt{7.5\times (7.5-2.4)\times (7.5-5.8)\times (7.5-6.8)}$
$=\sqrt{7.5\times 5.1\times 1.7\times 0.7}$
$=1.7\times \sqrt{7.5\times 3\times 0.7}$
$\approx 6.75c{m}^2$
Hence, the correct answer is option (d).