Question

The lengths of the sides of a triangular field are 20 m, 21 m and 29 m. The cost of cultivating the field at Rs. 9 per $m^2$ is

(a) Rs. 2610 (b) Rs. 3780 (c) Rs. 1890 (d) Rs. 1800

Answer 1

a = 20 m
b = 21 m
c = 29 m

$\sqrt{a^2+b^2}=\sqrt{{20}^2+{21}^2}=\sqrt{400+441}=\sqrt{841}=29=c$

The triangle is a right-angled triangle,

$Area=\frac{1}{2}\times b\times h$

$=\frac{1}{2}\times 20\times 21=210c{m}^2$

The cost of cultivating the field at Rs. 9 per $m^2=210\times 9=Rs.1890$