(_ = cosφ1 * sinΔλ) * _ + (_ = cosφ0 * sinφ1 - sinφ0 * cosφ1 * cosΔλ) * _
sinφ0 * sinφ1 + cosφ0 * cosφ1 * cosΔλ
(_ = cosφ1 * sinΔλ) * _
Math.pow(cosφ1 * sinΔλ, 2)
The only reason I can think of is performance. First let's test if they actually do the same and we didn't overlook something.
var test = (test = 5 * 2) * test; // 100 Math.pow(5 * 2, 2); // 100
As expected, that's proven to do the same. Now let's see if they have different performances using jsperf. Check it out here: http://jsperf.com/...num-self
The differences for Firefox 23 are very small, but for Safari the difference was much bigger. Using
Math.pow seems to be more expensive there.