Question

Look at the figure below:If siny - and tan yo =9-what is the value of cos yº? O cos y 90cos yOcos yO cos y® - 90

Answer 1

The trigonometric functions tangent, sine and cosine are related by the following equation:

`\tan \theta=(\sin \theta)/(\cos \theta)`

In this case, the angle is y°, so:

`\tan y\degree=(\sin y\degree)/(\cos y\degree)`

Since we want the cosine, we can solve for it ans substitute the given tangent and sine:

`\cos y\degree=(\sin y\degree)/(\tan y\degree)=((9)/(c))/((9)/(d))=(9)/(c)\cdot(d)/(9)=(d)/(c)`

This corresponds to the third alternative.