Angles [tex]\(X\)[/tex] and [tex]\(Y\)[/tex] are supplementary. Angle [tex]\(X\)[/tex] is 3 times the measure of angle [tex]\(Y\)[/tex]. What is the measure of angle [tex]\(Y\)[/tex]?

A. [tex]\(45^{\circ}\)[/tex]
B. [tex]\(60^{\circ}\)[/tex]
C. [tex]\(120^{\circ}\)[/tex]

Answer :

To find the measures of angles [tex]\( X \)[/tex] and [tex]\( Y \)[/tex] given that [tex]\( X \)[/tex] is 3 times the measure of [tex]\( Y \)[/tex] and they are supplementary angles, we will follow these steps:

1. Understand the concept of supplementary angles: Supplementary angles are two angles whose measures add up to [tex]\( 180^\circ \)[/tex].

2. Set up the relationship: Let [tex]\( Y \)[/tex] be the measure of angle [tex]\( Y \)[/tex]. We are given that angle [tex]\( X \)[/tex] is 3 times the measure of angle [tex]\( Y \)[/tex]. Thus, we can write:
[tex]\[ X = 3Y \][/tex]

3. Form the equation based on the supplementary relationship: Since [tex]\( X \)[/tex] and [tex]\( Y \)[/tex] are supplementary, their sum is [tex]\( 180^\circ \)[/tex].
[tex]\[ X + Y = 180^\circ \][/tex]

4. Substitute [tex]\( X \)[/tex] in the equation: Replace [tex]\( X \)[/tex] with [tex]\( 3Y \)[/tex] in the supplementary angle equation:
[tex]\[ 3Y + Y = 180^\circ \][/tex]

5. Simplify and solve for [tex]\( Y \)[/tex]: Combine like terms and solve for [tex]\( Y \)[/tex]:
[tex]\[ 4Y = 180^\circ \][/tex]
[tex]\[ Y = \frac{180^\circ}{4} \][/tex]
[tex]\[ Y = 45^\circ \][/tex]

6. Calculate the measure of angle [tex]\( X \)[/tex]: Since [tex]\( X \)[/tex] is 3 times the measure of [tex]\( Y \)[/tex], we have:
[tex]\[ X = 3 \times 45^\circ \][/tex]
[tex]\[ X = 135^\circ \][/tex]

Thus, the measures of angles [tex]\( Y \)[/tex] and [tex]\( X \)[/tex] are [tex]\( 45^\circ \)[/tex] and [tex]\( 135^\circ \)[/tex], respectively.