I've already found the bottom triangle's area (13.59m^2) but am having trouble finding an angle at the top to find the other triangle's area. The final answer should be 17.3m^2 but I'm not sure how to get there. Just need the workings out for question a. Any help would be really appreciated. Thanks!
Nevermind I ended up figuring it out.
I used 6^2+5^2-2*6*5*cos(65) = 35.64, (sqrt = 5.97) to find the length of the black line,
then 2.5^2+4^2-5.97^2/2*2.5*4 = -0.67, cos^-1(-0.67) = 132.04 to get the angle at b (top triangle)
and finally 0.5*2.5*4*sin(132.04) = 3.71, 3.71 + 13.59 = 17.3m^2
Area = 17.3m^2