Gujarat BoardEnglish MediumSTD 9MathsTriangles1 Mark
MCQ
In Fig. if $\text{AB}\perp\text{BC},$ then $x =$
A
$18^\circ$
✓
$22^\circ$
C
$25^\circ$
D
$32^\circ$
✓
Answer
Correct option: B.
$22^\circ$
$\text{AB}\perp\text{BC}$$\Rightarrow\angle\text{ABC}=90^\circ$
$\angle\text{CAB}=32^\circ$ (Opposite angles)
Now, in $\triangle\text{ABD}$
$\angle\text{DAB}=\text{x}^\circ+32^\circ$
$\angle\text{ABD}=90^\circ$
$\angle\text{BDA}=\text{x}^\circ+14^\circ$
In a $\triangle,$ sum of all angles $= 180^\circ$
$\Rightarrow\angle\text{DAB}+\angle\text{ABD}+\angle\text{BDA}=180^\circ$
$\Rightarrow\text{x}^\circ+32^\circ+90^\circ+\text{x}^\circ+14^\circ=180^\circ$
$\Rightarrow2\text{x}^\circ=180^\circ-136^\circ$
$\Rightarrow2\text{x}^\circ=44^\circ$
$\Rightarrow\text{x}^\circ=22^\circ$
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