Answer:
17.
Step-by-step explanation:
6^2 - 19
= 36 - 19
= 17.
The reasoning would be that it was given because there's no theorem or anything involved it was simply given to you already
check the picture below.

as you may already know, tan⁻¹ function has a range of (π/2, -π/2), and therefore it will give us the negative counterpart angle, however, the positive one we can get it by going the other way, 360 - θ.
Answer is
210m2
Hope this helps :)