Chapter 13, Problem 12QC

To determine

To find : The value of $\sin {225}^{\circ }$

Answer to Problem 12QC

  $-\frac{1}{\sqrt{2}}$

Explanation of Solution

Given information:

We know that, the given expression is $x^2-7x+12=0$

Formula used:

  $\cos ({180}^{\circ }+\text{θ})=-\cos \text{θ}$

Calculation :

  $\begin{array}{l}\Rightarrow \cos {225}^{\circ }\\ \Rightarrow \cos ({180}^{\circ }+{45}^{\circ })\\ \Rightarrow -\cos {45}^{\circ }\\ \Rightarrow -\frac{1}{\sqrt{2}}\end{array}$