Yes, set up your proportion: x/21 = 10/14
Cross multiply 14x = 210
Divide both sides by 14 and x= 15 cm
Let's use the furthest left point on the triangle to figure out the translation.
Blue triangle = (-5,1)
Black triangle = (-3,-1)
To get from -5 to -3 we moved the triangle 2 units to the right, which means that we added 2.
To get from 1 to -1, we moved the triangle 2 units down, which means we subtracted 2.
Rule: {2, -2}
Hope this helps!
See attachment for one such shell. The volume is given by the sum of infinitely many thin shells like this, each with radius

and height determined by the vertical distance between the upper blue curve and the lower orange curve for any given

, i.e.

.
The volume is then
The measure of the angle formed by 2 chords that intersect inside the circle is 1/2 the sum of the chords' intercepted arcs.
m∠RST = (143+33)/2 = 176/2 = 88°