Question

What is the sum of $30$ consecutive odd numbers starting from $1?$ $\left[1\right]$
(a) $150$ (b) $300$ (c) $600$ (d) $900$

Answer 1

Area of right angled triangle $=\frac{1}{2}\times \text{base}\times {\text{height (unit)}}^2$
Here, $\text{base}=4\text{cm, height}=5\text{cm}$
Area of right angled triangle $=\frac{1}{2}\times 4\times 5$
$=\frac{1}{2}\times 20$
$=10c{m}^2$