Answer

  1. 60°.
    Solution:
    Since ABCD is a parallelogram, AB || CD since opposite angles of a parallelogram are equal.
    $\Rightarrow\angle\text{ABD}=\angle\text{BCD}=45^{\circ}$ ...(Alternate angles)
    In $\triangle\text{ADB},$
    $\angle\text{ABD}+\angle\text{BDA}+\angle\text{DAB}=180^{\circ}$ ...(Angle sum property)
    $\Rightarrow45+\angle\text{BDA}+75=180$
    $\Rightarrow\angle\text{BDA}+120=180$
    $\Rightarrow\angle\text{BDA}=60^{\circ}$
    $\Rightarrow\angle\text{CBD}=\angle\text{BDA}=60^{\circ}$ ...(Alternate angles)
    $\Rightarrow\angle\text{CBD}=60^{\circ}$

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