I assume that the second one is :
[6 cot t]^2 = 108
36cot^2 t = 108 divide both sides by 36
cot^2 t = 3 take the square root of both sides
cot t = ± sqrt (3)
For the first soluton, we have
cot t = sqrt(3) this occurs at pi/6 + n*pi where n is an integer
For the second solution, we have
cot t = - sqrt(3) this occurs at 5pi/6 + n*pi where n is an integer
Here's the graph [in degrees] : https://www.desmos.com/calculator/hbl4cuxc3a
