IKMC 2019 - Grades 9-10 - Set 2 - Self-study Question 8

Question 8

Nine identical squares form the shown grid. Which relation between the marked angles is true?

1. $\alpha=\beta$
2. $2\alpha+\beta=90^\circ$
3. $\alpha+\beta=60^\circ$
4. $2\beta+\alpha=90^\circ$
5. $\alpha+\beta=45^\circ$