This involves trigonometry. Since we need to find the value of a, we need to find a trig equation with a as the numerator. Luckily, we have one, tan. So, tan(20) is equal to a/6, right. So, using a calculator, tan(20) is approximately equal to 0.363. This times 6 should equal a. This is approximately around 2.1. Thus our answer is 2.1
