Question

find the answer please

Answer 1

Given, O is the circumcenterConstruction: OC joined.
To prove: ∠OBC​+∠BAC = 900Proof:In ΔOBC OB = OC [∵radii of same circle]∴ΔOBC is isosceles∠OBC = ∠OCB= Angles opposite to equal sides of an isosceles triangle]Again,∠BOC =2∠BAC

∠OBC+∠OCB+BOC=180
=Sum of angles of a triangle
=>2∠OBC + 
BOC =1800 [∵By eqn. 1]
=>2∠OBC+2

BAC=1800 [∵By eqn. 2]

=>∠OBC+∠BAC=18002=90

=>∠OBC+∠BAC = 90