Given:
The measures of the angles in a triangle are in the ratio of 2:2:4.
To find:
The exterior angle that is adjacent to the largest angle.
Solution:
Let the interior angles of the triangle are 2x, 2x and 4x respectively.
According to the angle sum property, the sum of interior angles of a triangle is 180 degrees.
[tex]2x+2x+4x=180^\circ[/tex]
[tex]8x=180^\circ[/tex]
[tex]x=\dfrac{180^\circ}{8}[/tex]
[tex]x=22.5^\circ[/tex]
Clearly, x=22.5>1, so 4x is the largest angle between 2x, 2x and 4x.
Now,
[tex]\text{Largest angle}=4x[/tex]
[tex]\text{Largest angle}=4(22.5^\circ)[/tex]
[tex]\text{Largest angle}=90^\circ[/tex]
Let the required exterior angle that is adjacent to the largest angle be y.
Interior angle and adjacent exterior angles are supplementary, so their sum is 180 degrees.
[tex]\text{Largest angle}+y=180^\circ[/tex]
[tex]90^\circ+y=180^\circ[/tex]
[tex]y=180^\circ-90^\circ[/tex]
[tex]y=90^\circ[/tex]
Therefore, the exterior angle that is adjacent to the largest angle is 90°.