How do you solve $cot 2a = 5/12$ ?

Question

3151 views around the world

You can reuse this answer
Creative Commons License

Answer 1 · 2015-05-26T02:32:26

$cot 2a = 1/(tan 2a) = 5/12$

$tan 2a = 12/5 = 2.4$ .

Calculator gives 2a = 67.38 --> $a = 33.69$ deg

Trig unit circle gives another arc that has the same (tan 2a) value:

2a = 67.38 + 180 = 247.38.. -> $a = 123.69$

Answer 2 · 2015-05-26T03:03:55

$cot 2alpha$ implies cotangent of angle $2alpha$ , therefore $2alpha$ = arc tan $12/5$ and that works out to 67.38 degree. So, $alpha$ =33.69 degrees

How do you solve cot 2a = 5/12cot 2a = 5/12?