Question about arc length

[jefff]

According to my teacher that work is right, but how can the length of the arc (.2853) be shorter than the interval (-pi/4 to pi/4 = pi/2)?

 

[mmm4444bot]

I'm having trouble visualizing the curve.

sqrt[sin(t)^4 - 1] is not a continuous function.

The only values in its domain are odd multiples of Pi/2.

The only value in its range is zero.