The area of an isosceles triangle is given by
[tex]Area = base \: \times height[/tex]
We have the base already given, so we just have to calculate the height using the sine ratio.
[tex] \sin(57 \degree) = \frac{h}{14} [/tex]
[tex] \Rightarrow h = 14 \times \sin(57 \degree) [/tex]
You may choose to use your calculator here, but I will prefer to keep it as it is and use the calculator value at the end.
Now let's plug our values inside the formula, yo obtain,
[tex]Area = 20 \times 14 \sin(57 \degree) [/tex]
[tex]Area = 234.8 {cm}^{2} [/tex]
[tex]<b>Hence, the area of the parallelogram is 234.8cm²</b>[/tex]
