Explanation:
let's name the 2 sides of the bisected angle a and b.
and the 2 segments (created by the bisector) of the opposite side x and y.
then we have
a/b = x/y
question 1
14/21 = x/15
1/3 = x/15
15/3 = x = 5
question 2
8/y = 4/6
8×6 = 4y
48 = 4y
y = 12
question 3
3/4.5 = z/1.5
3×1.5 = 4.5z
4.5 = 4.5z
z = 1
question 4
16.5/p = 11/(29-11) = 11/18
16.5×18 = 11p
297 = 11p
p = 27
question 5
7/13 = (15-x)/x
7x = 13×(15-x) = 195 - 13x
20x = 195
x = 195/20 = 39/4 = 9.75