Question

In the figure above, find the value of $a$ given that $x\parallel y$.

• A. $b+c$
• B. $2b-c$
• C. $180-b+c$
• D. $180-b-c$

Answer 1

Answer: (D)

$180-b-c$

Since $x||y$, the third angle in the triangle having $a^o$ and $b^o$, as two of its angles becomes $c^o$.

Using the equality of corresponding angles and vertically opposite angles.

$\therefore a^o+b^o+c^o={180}^o$ .... since they are angles of a triangle.

$\therefore a=180-b-c$