First find the critical points of <em>f</em> :



so the point (1, 0) is the only critical point, at which we have

Next check for critical points along the boundary, which can be found by converting to polar coordinates:

Find the critical points of <em>g</em> :



where <em>n</em> is any integer. We get 4 critical points in the interval [0, 2π) at




So <em>f</em> has a minimum of -7 and a maximum of 299.
The first one is 25/9
And the second one is 25/36
8 sin2x - 10sinxcosx = 8*2sinXcosX-10sinXcosX = 16sinXcosX - 10sinXcosX = 6sinXcosX=3sin2x
The difference between 1/8 and 6/10 = 0.475 , does this help?