I tried using 4 but didn't get it and it's frustrating me! I think it's because of that small gap going up at the F. Would you be able to give me the the sides to use, as I don't know how to do it when only a small part of the curve is being used. Here's my working:



I have:

Area = CDEF + BCFG - DAFE - ABGF

CDEF = 1.8 x 0.3 = 0.54

ABGF = 0.9 x 0.3 = 0.27

BCFG = f (0.72/V) limits of b = 2.5 and a = 0.5

= 0.72ln(V)

= [(0.72ln(2.5)) - (0.72ln(0.5))]

= 1.258795297

DAFE = f (1.8/V) limits of b = 0.4 and a = 0.2

= 1.8ln(V)

= [(1.8ln(0.4)) - (1.8ln(0.2))]

= 1.247884925

Area = 0.54 + 1.158795297 - 1.1247664925 - 0.27

=0.181130372 * 100

=18.1130372

But the real answer is 118.7