Use the data in the drawing to calculate the \alpha angle (Sorry, I'm not a native english speaker)

Question

Use the data in the drawing to calculate the
`\alpha` angle

(Sorry, I'm not a native english speaker)

Answer 1

Sum of the opposite angles of a cyclic quadrilateral is 180°

`\alpha + 50 = 180 \\ \alpha = 180 - 50 \\ \boxed{\alpha = 130}`

130° is the right answer.

Answer 2

Explanation:

Opposite angles in a cyclic quadrilateral

are supplementary. (Sum up to 180°)

Hence alpha + 50° = 180°,

Alpha angle = 130°.