Desmos Graphing Calculator

CalcReferenceCopy

Math·Geometry and Trigonometry·Right triangles and trigonometry

medium

In right triangle $RST$, the sum of the measures of angle $R$ and angle $S$ is $90\text{ degrees}$. The value of $\sin (R)$ is $\frac{2\sqrt{10}}{7}$. What is the value of $\cos (S)$?

A

$\frac{3\sqrt{10}}{20}$

B

$\frac{2\sqrt{10}}{7}$

C

$\frac{7\sqrt{10}}{20}$

D

$\frac{2\sqrt{10}}{3}$