Question

If $\angle A$ and $\angle B$ are complementary angles and $m\angle A$ is $x^o$, which equation can be used to find $m\angle B$ which is denoted by $y$?

• A. $y=(90+x{)}^o$
• B. $y=(90-x{)}^o$
• C. $y=(180x{)}^o$
• D. $y=(x+180{)}^o$

Answer 1

Answer: (B)

$y=(90-x{)}^o$

If $\angle A$ and $\angle B$ are complementary angles, then

$m(\angle A+\angle B)={90}^o$

Now, it is given that $m\angle A=x^o$ and $m\angle B$ is denoted by $y$.

So, we have $\Rightarrow x^o+y^o={90}^o\Rightarrow y=(90-x{)}^o$