Can you help me solve them

3. Given is a quadrilateral ABCD. A circle of radius 4 cm is inscribed in it. If AB = 6 cm and CD = 12 cm, find the area of ABCD. 4. Find the radius of the inscribed circle in quadrilateral ABCD if the area of ABCD is 240 cm2. 5. Find the area of a quadrilateral is its diagonals are 5 cm and 8 cm, and the angle between them is 450. 6. Find the angle measure of a regular polygon with 20 sides. 7. Find the number of sides of a regular polygon with angle measure 1650. 8. Find the central angle of the circumscribed circle around a polygon with 10 sides. 9. Find the radii of the inscribed and circumscribed circles for a regular 12-gon with a side 20 cm. 10. Find the side and the area of a regular polygon if the radius of its inscribed circle is 8 cm. 11. Find the side and the area of a regular polygon if the radius of its circumscribed circle is 10 cm