1. Let us find the area of the sector:
[tex]\begin{gathered} \frac{\theta}{360}\cdot\pi\cdot r^2\text{ (Area of a sector formula)} \\ \frac{85}{360}\cdot\pi\cdot(12\operatorname{cm})^2\text{ (Replacing)} \\ \frac{85}{360}\cdot\pi\cdot144cm^2\text{ (Raising 12 to the power of 2)} \\ 0.236\cdot\pi\cdot144cm^2\text{ (Dividing)} \\ 106.814cm^2\text{ (Multiplying)} \end{gathered}[/tex]
2. The area of the triangle would be:
[tex]\begin{gathered} At=\frac{1}{2}\cdot ab\cdot\sin (\theta)\text{ (Area of a non right-angled triangle)} \\ At=\frac{1}{2}\cdot(12)\cdot(12)\cdot\sin (85)\text{ (Replacing)} \\ At=71.726cm^2 \end{gathered}[/tex]
3. Subtracting the area of the triangle from the area of the sector, we have:
106.814 cm^2 - 71.726 cm^2 = 35.088 cm^2
The answer is 35.088 cm^2
