Trig is useful to at least know the unit circle for sin/cos/tan: http://crystalclearmaths.com/wp-content/uploads/2015/11/Unit-Circle.jpg http://crystalclearmath

Trig is useful to at least know the unit circle for sin/cos/tan: http://crystalclearmaths.com/wp-content/uploads/2015/11/Unit-Circle.jpg http://crystalclearmaths.com/wp-content/uploads/2015/11/Unit... (Amusingly I had to learn about this outside of class, but it carried me through) Trig isn't so useful if you can measure everything, & I've made the mistake of using trig to skip measuring only to find that nothing's built straight. But it helps to ball park Once was sitting on the edge of a river with my father & he raised the question of how wide the river was. A quick estimate was possible: stand straight across from a landmark point, then measure walking along the river for some distance. Measure the angle towards that previous landmark. Multiply traveled length by tan(angle). A particularly nice angle is 45 degrees, which requires very little math since tan(45) = 1 & 45 is an easy angle to eye ball