Answer:
Explanation:
We are given :
and
………………………………………………
The lines AM and UK are perpendicular to the same line MN.
Then
We also have :
Therefore ,
………………………………………………………
∠MBK and ∠UBN are two vertically opposite angles.
Then
m∠MBK = m∠UBN
Since , m∠UBN = 90°
Then
m∠MBK = 90°