We have a right triangle, and we have one angle, the measure of the hypotenuse, we have that the side, x, is adjacent to the angle that measures 21°:
Since we have a right triangle (one of its internal angles equals 90 degrees), we can use the trigonometric ratios. Since we have that the adjacent side to 21 is x and the value for the hypotenuse is 10, then we can use the cosine ratio as follows:
[tex]cos(\theta)=\frac{\text{ Adjacent side}}{\text{ Hypotenuse}}[/tex]
Therefore, we have:
[tex]cos(21^{\circ})=\frac{x}{10}[/tex]
Now, we need to multiply both sides of the equation by 10 as follows:
[tex]\begin{gathered} 10*cos(21^{\circ})=10(\frac{x}{10})=x \\ \\ x=10*cos(21^{\circ}) \\ \\ x=9.33580426497 \end{gathered}[/tex]
Therefore, in summary, if we round our result to the nearest tenth, we have that the value for x = 9.3.
