Answer:
A= 145.12mm^2
Explanation:
The diagram shows us a Right angle triangle; so, I use Phythagoras' Theorem, to find length of the base.
c^2 - b^2 = a^2
27^2-12^2 =a^2
585. = a^2
Square root both sides
a = root 585
= 24.18677324
A= bxh/2
= root 585 x 12/2
= 18 root 65
= 145.1206395
A= 145.12mm^2 to 2.d.p
(Haven't rounded up in calculations until the end. Thus, using the exact values of root 585,for example. )
Hope this helps!