Question

In right angle $△ABC,\angle B={90}^o,\angle A={45}^o$, then $\tan {45}^o=$

• A. $1$
• B. $\sqrt{2}$
• C. $\frac{1}{\sqrt{2}}$
• D. None of above

Answer 1

The correct option is A $1$

$\angle A=\angle C\Rightarrow AB=BC=a$

So $AC=\sqrt{{AB}^2+{BC}^2}=\sqrt{a^2+a^2}=\sqrt{2a^2}=\sqrt{2}a$

$\tan 45=\frac{BC}{AB}=\frac{a}{a}=1$

So $1$ is correct.