Question

In Figure 17, determine the value of x ?

Answer 1

Answer:

$x + x = 138 \: {vertically \: opposite \: angle} \\ 2 x = 138 \\ x= 69 \\ answer$

Answer 2

x = 69

let the two vertically opposite angles be y and z.

y = z.

also, 138 + y = 180

y = 42

x + x + 138 + the two vertically opp. angles = 360°

2x + 138 + 42 + 42 = 360

2x + 138 + 84 = 360

2x + 222 = 360-222

2x = 138

x = 69