Since ∆AFB is similar to ∆ABC.
<u>In </u><u>∆</u><u>A</u><u>BC,</u>
⇛< A + < B + < C = 180°
⇛37° + 65° + < C = 180°
⇛102° + < C = 180°
⇛< C = 78°
We know that, < AGF / < G = < C
So, Measure of angle < AGF = <u>7</u><u>8</u><u>°</u><u> </u><u>(</u><u>ans)</u>
The disk method will only involve a single integral. I've attached a sketch of the bounded region (in red) and one such disk made by revolving it around the y-axis.
Such a disk has radius x = 1/y and height/thickness ∆y, so that the volume of one such disk is
π (radius) (height) = π (1/y)² ∆y = π/y² ∆y
and the volume of a stack of n such disks is
where is a point sampled from the interval [1, 5].
As we refine the solid by adding increasingly more, increasingly thinner disks, so that ∆y converges to 0, the sum converges to a definite integral that gives the exact volume V,
