`A B C D` is a parallelogram, `M` is the mid-point of `B D` and `B M` bisects `/_B` . Then, `/_A M B=` `45^@` (b) `60^@` (c) `90^@` (d) `75^@`

Explanation

In parallelogram ABCD, M is the mid-point of BD and BM bisects
`angleB` and `AM` is joined.

As, we know that the diagonals of a parallelogram bisect each other then, AC will pass thought M.

`therefore` BM bisects `angleB`

So, `angle1=angle2`

`AD|\|BC`, `DB` is the tranversal.

Now, `angle2=angle3`_______1 (alternate interior angles)

`angle1=angle2=angle3`____2

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