Answer:
Here,
X°+ 51°+42°=180°( being sum of three angle of a triangle)
or, X°+93°=180°
or, X°=180°-93°
.°. X°= 87° ans.
Now,
<D + 42°=180°( being angle in a straightline)
or, <D=180°- 42°
.°. <D= 138° ans.
Hope this helps you!
x = 87
Add all of the known measurements in the triangle then subtract it from 180. The difference is the value of x. To find the measure of D, a straight line is equal to 180 so subtract 180 from 42 degrees.
51 + 42 = 93
180 - 93 = 87
180 - 42 = 138
m<D = 138
