Finding Common area under some polynomial curve

Hello Guys, I am new to Matlab and got stuck with this problem.Actually, I need to find the shaded area as shown in the picture.I have a polynomial curve of 8 order with coefficients 76.4083184414468 -6371.86069367096 238457.663626450 -5313777.50319281 77602092.9842676 -754371232.479583 4656620413.14696 -16084108155.9535 23191234884.0141.For simplicity, the smaller value can be assumed and I have a line y= (some const.) that cuts this curve at 2 points and now I want to find the area of the rectangle that fits exactly inside this curve. And later on, I want to calculate the area of the rectangle for different values of constants. Any help would be thankful

Answer 1

[Soumya Saxena]

Please consider using "trapz" function :

https://www.mathworks.com/help/matlab/ref/trapz.html