Draw a right triangle.
Designate an acute angle, Angle a.
Label the legs consistent with the given value of the tangent of 'a'.
Contemplate the hypotenuse.
Thanks TKHunny, I only got this far with your explanation but it sounds intersting if if could help with these types of questions, I can never get them right.
I know that I should surely be able to understand but I don't, I wouldn't be asking if I did. I don't get it
Don't overthink this.
You have essentially said at the beginning of the question (correctly):
Let
In order for both sides of the equation to be equal, both sides have to have
This means that, looking at the right hand side, .
Both sides have to have .
So, looking at the right hand side,
And then it's just an application of