formula for interior angles of a polygon is 180 times the number of sides minus 2
20 a 20gon has 20 sides, 20 -2 = 18, 180*18 = 3240
sum of interior angles = 3240 degrees
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The amount of the tip is 12%
1. BC is 1+3=4 (units)
2. AD is 3+5= 8 (units)
3. Draw the altitude CH from point C, as shown in the figure.
4. Then triangle CHD is a right triangle, with hypothenuse CD, and sides HD and CH.
5.



6. AB=CD=4.47 because the trapezoid is isosceles.
7. P= BC+AD+AB+CD=4+8+4.47+4.47=20.9 (units)
Answer:
3x³+10x²-8x-2
Step-by-step explanation:
(-3x³+7x²-8x+11)-(-3x²+13)
- remove unnecessary parentheses
-3x³+7x²-8x+11-(-3x²+13)
-3x³+10x²-8x+11-13
-3x³+10x²-8x-2