Question

Area of each small square is $1c{m}^2$. So, what is the area of red triangle?

• A. $15c{m}^2$
• B. $20c{m}^2$
• C. $10c{m}^2$
• D. $1c{m}^2$

Answer 1

Answer: (C)

$10c{m}^2$

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 $=12c{m}^2$

and Area of green rectangle $=8c{m}^2$

Now, Area of orange portion of the triangle $=\frac{\text{Area of orange rectangle}}{2}=\frac{12}{2}=6c{m}^2$

and,Area of green portion of the triangle $=\frac{\text{Area of green rectangle}}{2}=\frac{8}{2}=4c{m}^2$

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

$=(6+4)c{m}^2=10c{m}^2$