Which statement can be concluded using the true statements shown?

If two angles in a triangle measure [tex]\(90^{\circ}\)[/tex] and [tex]\(x\)[/tex] degrees, then the third angle measures [tex]\((90-x)\)[/tex] degrees. In triangle [tex]\(ABC\)[/tex], angle [tex]\(A\)[/tex] measures [tex]\(90^{\circ}\)[/tex] and angle [tex]\(B\)[/tex] measures [tex]\(50^{\circ}\)[/tex].

A. Angle [tex]\(C\)[/tex] must measure [tex]\(50^{\circ}\)[/tex].
B. Angle [tex]\(C\)[/tex] must measure [tex]\(40^{\circ}\)[/tex].
C. Angle [tex]\(C\)[/tex] must measure [tex]\((90-40)\)[/tex] degrees.
D. Angle [tex]\(C\)[/tex] must measure [tex]\((90-30)\)[/tex] degrees.



Answer :

To solve the problem of finding the measure of angle [tex]\(C\)[/tex] in triangle [tex]\(ABC\)[/tex], given the measures of angles [tex]\(A\)[/tex] and [tex]\(B\)[/tex], let's follow these steps:

1. Recognize the given information:
- Angle [tex]\(A\)[/tex] measures [tex]\(90^\circ\)[/tex].
- Angle [tex]\(B\)[/tex] measures [tex]\(50^\circ\)[/tex].

2. Recall the key property of a triangle:
- The sum of the interior angles in any triangle is always [tex]\(180^\circ\)[/tex].

3. Set up an equation using this property:
- Let angle [tex]\(C\)[/tex] be the unknown angle.
- According to the angle sum property, we have:
[tex]\[ \angle A + \angle B + \angle C = 180^\circ \][/tex]

4. Substitute the given angle measures into the equation:
- Substitute [tex]\( \angle A = 90^\circ \)[/tex] and [tex]\(\angle B = 50^\circ \)[/tex] into the equation, giving:
[tex]\[ 90^\circ + 50^\circ + \angle C = 180^\circ \][/tex]

5. Solve for [tex]\(\angle C\)[/tex]:
- Combine the known angle measures:
[tex]\[ 140^\circ + \angle C = 180^\circ \][/tex]
- Subtract [tex]\(140^\circ\)[/tex] from both sides to isolate [tex]\(\angle C\)[/tex]:
[tex]\[ \angle C = 180^\circ - 140^\circ \][/tex]
- Simplify the expression:
[tex]\[ \angle C = 40^\circ \][/tex]

Given these steps, the correct conclusion is that [tex]\(\angle C\)[/tex] must measure [tex]\(40^\circ\)[/tex].

Therefore, based on the possible answer choices:

- Angle [tex]\(C\)[/tex] must measure [tex]\(40^\circ\)[/tex] is the correct statement.

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