The length of an arc is given by θ/360×2πr, where θ is angle subtended by the arc to the center and r is the radius of the circle.
The length is 12 units, and θ/360 is 1/3
Therefore, 12 = 1/3 × 3.142 ×r
r = 12× 3/3.142
r = 11.457 units
≈ 11 units
The anwer plus working is 6668/4=151.55
16x^4-81y^4 difference of perfect squares...
(4x^2-9y^2)(4x^2+9y^2) that's one of the equivalents...
(2x+3y)(2x-3y)(4x^2+9y^2) that's another one of them...
