Explanation:
how could you solve 10., if you cannot solve 11. ? they are using the same thing : law of sine.
a/sin(A) = b/sin(B) = c/sin(C)
a, b, c being the sides, and A, B, C being the corresponding opposite angles.
11.
x/sin(90) = 13/sin(70)
as sin(90) = 1
x = 13/sin(70) = 13.83431104...
13.
remember, the sum of all angles in a triangle is always 180°.
angle JLM = 180 - 90 - 51 = 39°
angle LJK = 180 - 90 - 72 = 18°
14/sin(39) = JL/sin(51)
JL = 14×sin(51)/sin(39)
JL/sin(90) = JL = 14×sin(51)/sin(39) = KL/sin(18)
KL = 14×sin(51)×sin(18)/sin(39) = 5.342458907...