I have forgotten the growth rate formula, the reduction rate formula, the area of a circle, the area of a sector and the arc length formula

I have forgotten the growth rate formula, the reduction rate formula, the area of a circle, the area of a sector and the arc length formula

Because the sector = two radii + arc length, if the radius is R and the center angle of the sector is n °, then the sector perimeter: C = 2R + n π R △ 180, the sector area formula is in the circle with radius r, because the area of the sector opposite to the center angle of 360 ° is the circle area s = π R ^ 2, so the sector area with center angle of n ° is s = n π R