The missing justification in the proof is
<span>B) Substitution property of equality
The expression for sin</span>² x and cos² x is substituted to the other side of the equation. Since sin x = a/c, then sin² x = a²/c². Similarly, since cos x = b/c, then cos² x = b²/c². Adding to two results to the third statement.
The two angles shown are vertical angles. They form when you cross two lines. They are opposite one another. Note: They don't have to be vertically up and down in relation to each other. It's possible to have them horizontally side by side like this.
So because they are vertical angles, they are congruent. This means they are equal in measure
x+90 = 4x
x+90-x = 4x-x
90 = 3x
3x = 90
3x/3 = 90/3
x = 30
Therefore the answer is choice C) The value of x is x = 30
We can check it by plugging this into the original equation above
x+90 = 4x
30+90 = 4*30
120 = 120
our answer checks out
Yes I agree with the last person, it’s Line D.
