Question

Area of each small square is $$1\,cm^2$$. So, what is the area of red triangle?

Answer 1

Correct option is C. $$10cm^2$$
There are two rectangles in the above figure i.e., orange and green.

Orange rectangle contains $$12$$ squares and green rectangle contains $$8$$ squares.

Thus, Area of orange rectangle $$=12\space\mathrm{cm^2}$$

and Area of green rectangle $$=8\space\mathrm{cm^2}$$

Now, Area of orange portion of the triangle $$=\dfrac{\text{Area of orange rectangle}}{2}=\dfrac{12}{2}=6\space\mathrm{cm^2}$$

and, Area of green portion of the triangle $$=\dfrac{\text{Area of green rectangle}}{2}=\dfrac{8}{2}=4\space\mathrm{cm^2}$$

Thus, Area of red triangle $$=$$ Area of orange portion of the triangle $$+$$ Area of green portion of the triangle

$$=(6+4)\space\mathrm{cm^2}=10\space\mathrm{cm^2}$$