## Isosceles Triangles

Example:

For the isosceles
triangle depicted below, determine the angles x and y, in addition to
length from A
to C.

As the triangle is
isosceles, it follows that AC = AB.

∴ AC = 8

∴ AC = 8

m∠x = 70°

Since the sum of interior angles for a triangle equals 180°:

m∠x + 70° + m∠y = 180°

Since m∠x = 70° from above:

70° + 70° + m∠y = 180°

m∠y = 180° − 70° − 70°

m∠y = 40°

Since the sum of interior angles for a triangle equals 180°:

m∠x + 70° + m∠y = 180°

Since m∠x = 70° from above:

70° + 70° + m∠y = 180°

m∠y = 180° − 70° − 70°

m∠y = 40°

(Note: Inclusion of data regarding BC in the problem was merely a distractor as it was not needed to solve the problem.)

Related Topics: