Answer:
The answer is the option [tex]21\ units^{2}[/tex]
Step-by-step explanation:
we know that
In this problem the area of parallelogram RSTU is equivalent to the sum of the area of the right triangle RUS and the area of the right triangle UST
Remember that
The area of a triangle is equal to
[tex]A=\frac{1}{2}bh[/tex]
Find the area of triangle RUS
we have
[tex]b=US=7\ units[/tex] -----> observing the figure
[tex]h=RU=3\ units[/tex] -----> observing the figure
substitute
[tex]A1=\frac{1}{2}(7)(3)=\frac{21}{2}\ units^{2}[/tex]
Find the area of triangle UST
we have
[tex]b=US=7\ units[/tex] -----> observing the figure
[tex]h=ST=3\ units[/tex] -----> observing the figure
substitute
[tex]A2=\frac{1}{2}(7)(3)=\frac{21}{2}\ units^{2}[/tex]
The area of parallelogram is the sum of the area of two triangles
so
[tex]A=A1+A2[/tex]
substitute
[tex]A=\frac{21}{2}\ units^{2}+\frac{21}{2}\ units^{2}=21\ units^{2}[/tex]
