It is known that the length of the side edge of the regular triangular prism abc-a1b1c1 is equal to the length of the side edge of the bottom, then the sine of the angle between Ab1 and acc1a1 is equal to () A. 64B. 104C. 22D. 32

It is known that the length of the side edge of the regular triangular prism abc-a1b1c1 is equal to the length of the side edge of the bottom, then the sine of the angle between Ab1 and acc1a1 is equal to () A. 64B. 104C. 22D. 32

Take the midpoint D1 of a1c1, connect b1d1 and AD1. In the regular triangular prism abc-a1b1c1, b1d1 ⊥ face acc1a1, then ∠ b1ad1 is the angle formed by Ab1 and side acc1a1, ∵ the side edge length of regular triangular prism abc-a1b1c1 is equal to the side length of bottom surface, ∵ sin ∵ b1ad1 = 322 = 64, so select a