Chapter 54, Problem 1A

Determine the size of ∠1.

To determine

The size of $\angle 1$.

Answer to Problem 1A

The size of $\angle 1$ is ${24}^o$.

Explanation of Solution

Given information:

The two angles of a triangle are given.

  $\angle 2={109}^o$

  $\angle 3={47}^0$

Calculation:

According to trigonometry rule:

The sum of all the angles of a triangle is ${180}^o$.

So,

  $\begin{array}{l}\angle 1+\angle 2+\angle 3=180\\ \angle 1+109+47=180\\ \angle 1=180-109-47\\ \angle 1={24}^O\end{array}$