Gujarat BoardEnglish MediumSTD 7MATHSLines and Angles1 Mark
MCQ
The angle which is one - fifth of its complement is:
✓
$15^\circ$
B
$30^\circ$
C
$45^\circ$
D
$60^\circ$
✓
Answer
Correct option: A.
$15^\circ$
We need to find out Angle which is $\frac{1}{5}$ of its complement is:
Let, the angle be $x$
$\therefore$ Its complement is $(90 - x)$ According to the question,
$\text{x}=\frac{1}{5}\times(90-\text{x})\text{x}=18-\frac{\text{x}}{5}$
Now, $\text{x}+\frac{\text{x}}{5}=18$
$\therefore\frac{5\text{x}+\text{x}}{5}=18$
or $\frac{6\text{x}}{5}=18$
or $6\text{x}=90$
$\therefore\text{x}=15^\circ$
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