An exterior angle of a triangle equals minus the adjacent interior angle.

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An exterior angle of a triangle equals 180° minus the adjacent interior angle.

Step-by-step explanation:

The two angles are said to be adjacent if they have a common vertex and a common side between them.

So, if an angle is exterior to any angle of a triangle, But that particular angle of a triangle is adjacent to the exterior angle. Then, The both angles must lie on the straight line and thus both will form a linear pair.

The measure of the linear pair is always supplementary.

⇒ Exterior angle + Adjacent interior angle = 180°

⇒ Exterior angle = 180° - Adjacent interior angle

Hence, An exterior angle of a triangle equals 180° minus the adjacent interior angle.

{x = -1/2 ,   y = -1

step-by-step explanation:

solve the following system:

{2 x + y = -2

{10 x - 3 y = -2

in the first equation, look to solve for y:

{2 x + y = -2

{10 x - 3 y = -2

subtract 2 x from both sides:

{y = -2 x - 2

{10 x - 3 y = -2

substitute y = -2 x - 2 into the second equation:

{y = -2 x - 2

{10 x - 3 (-2 x - 2) = -2

10 x - 3 (-2 x - 2) = (6 x + 6) + 10 x = 16 x + 6:

{y = -2 x - 2

{16 x + 6 = -2

in the second equation, look to solve for x:

{y = -2 x - 2

{16 x + 6 = -2

subtract 6 from both sides:

{y = -2 x - 2

{16 x = -8

divide both sides by 16:

{y = -2 x - 2

{x = -1/2

substitute x = -1/2 into the first equation:

{y = -1

{x = -1/2

collect results in alphabetical order:

answer:   {x = -1/2 ,   y = -1