Explanation:
remember the basic trigonometry setup ?
the norm circle (radius = 1) with a horizontal and a vertical line through the center of the circle.
and then there is an angle at the center indicated by the horizontal line and an inclined (by that angle) radius line connecting the center and the circle arc.
this inclined radius line is then the baseline (Hypotenuse) of a right-angled triangle, and the legs of that triangle are sine and cosine of the angle at the center (sine is the vertical leg, cosine is the vertical leg).
in essence (at least it works for me), when given such right-angled triangle problems, I always try to rotate and/or flip this triangle until it looks like the described situation above.
the only other thing to remember is that for triangles inside circles with a different radius than 1, everything is multiplied by the actual radius (it really happens also for the norm circle, but multiplying by 1 does not really change anything, right ?).
so, now for the given problems :
1)
x is the radius of the circle.
we can make 68° the defining angle of that trigonometric situation. so, the top right vertex would be the center of the circle with radius x.
then
30 = cos(68)×x
x = 30/cos(68)
= 80.08401488...
2)
60 is the radius of the circle.
x is the defining angle.
then
15 = sin(x)×60
sin(x) = 15/60 = 1/4
x = 14.47751219...°
3)
x is the radius of the circle.
22° is the defining angle.
then
14 = cos(22)×x
x = 14/cos(22)
= 15.0994864...
4)
the unnamed side is the radius of the circle. let's call it "s".
54° is the defining angle.
then
47 = cos(54)×s
x = sin(54)×s
x/47 = sin(54)×s / (cos(54)×s) = sin(54)/cos(54) = tan(54)
x = 47×tan(54) or 47×sin(54)/cos(54)
= 64.68995026...
5)
14 is the radius of the circle.
41° is the defining angle.
then
x = sin(41)×14
= 9.184826406...
6)
the unnamed side is the radius of the circle. let's call it "s".
x is the defining angle.
then
57 = cos(x)×s
9 = sin(x)×s
9/57 = sin(x)×s / (cos(x)×s) = sin(x)/cos(x) = tan(x)
x = 8.972626615...°