Answer
$18$ square centimeters
Work Step by Step
The area $A$ of a triangle is given by the formula $A=\frac{1}{2}bh$ where $b$ is the base and $h$ is the height.
Substitute the given values into the formula to obtain:
$A=\frac{1}{2}bh$.
$A=\frac{1}{2}(4\text{ cm})(9\text{ cm})$
$A=18\text{ cm}^2$
Hence, the area of the triangle is $18$ square centimeters.
