Sector area formula: S=πR? α/360 =RL/2

Sector arc length formula: l = π r α/ 180.

Among them:

S- area; R- radius; α-central angle; L- arc length.

This is your desk:

1. 1，from L =πrα/ 180:α= 180 L/πr = 180 x 12/(56.52 x 3. 14

1.2, from S=πR? α/360 = RL/2:S = 12x 56.52/2 = 339. 12mm

2. 1, which is obtained from L = π r α/ 180: l = 3.14x2x72/180 = 2.512cm.

2.2, from S=πR? α/360 = RL/2:s = 2x 2.5 12/2 = 2.5 12cm。

3. 1, from S=πR? α/360:r =√ 13.083 x360/(πX60)=√25 = 5dm。

3.2. From L = π rα/ 180, L = 5x60x3.14/180 = 5.23 dm.

4. 1, which is obtained from L = π r α/ 180: r =180 l/α π =180 π/(18 π) =10m.

4.2, from S=πR? α/360 = rl/2； S= 10π/2=5πm？

Please note that the units are different.