given that cos0=sqrt2/5 of a triangle on the unit circle what is the sine ratio of the same triangle

1 answer

To find the sine ratio of the triangle given that \(\cos(\theta) = \frac{\sqrt{2}}{5}\), you can use the Pythagorean identity:

\[ \sin^2(\theta) + \cos^2(\theta) = 1 \]

First, substitute the value of \(\cos(\theta)\):

\[ \sin^2(\theta) + \left(\frac{\sqrt{2}}{5}\right)^2 = 1 \]

Calculating \(\left(\frac{\sqrt{2}}{5}\right)^2\):

\[ \sin^2(\theta) + \frac{2}{25} = 1 \]

Next, isolate \(\sin^2(\theta)\):

\[ \sin^2(\theta) = 1 - \frac{2}{25} \]

Convert 1 into a fraction with the same denominator:

\[ 1 = \frac{25}{25} \]

Now, perform the subtraction:

\[ \sin^2(\theta) = \frac{25}{25} - \frac{2}{25} = \frac{23}{25} \]

Now take the square root to find \(\sin(\theta)\):

\[ \sin(\theta) = \pm \sqrt{\frac{23}{25}} = \pm \frac{\sqrt{23}}{5} \]

The sine value will depend on the quadrant in which the angle \(\theta\) is located. If \(\theta\) is in the first quadrant, \(\sin(\theta)\) is positive:

\[ \sin(\theta) = \frac{\sqrt{23}}{5} \]

If \(\theta\) is in the second quadrant, \(\sin(\theta)\) remains positive, so:

\[ \sin(\theta) = \frac{\sqrt{23}}{5} \]

Thus, the sine ratio of the triangle is:

\[ \sin(\theta) = \frac{\sqrt{23}}{5} \]