+1995 1. Angle α lies in quadrant II , and tanα=−12/5 . Angle β lies in quadrant IV , and cosβ=3/5 .
What is the exact value of cos(α+β) ?
Enter your answer in the box.
cos(α+β) =
Second question deleted by Melody.
One question per post and see if you can learn from the first answer before you post the second question.
+118673 1. Angle α lies in quadrant II , and tanα=−12/5 . Angle β lies in quadrant IV , and cosβ=3/5 .
What is the exact value of cos(α+β) ?
Enter your answer in the box.
Remember that
sin(angle) is the y value over the hypotenuse.
cos(angle) is the x value over the hypotenuse.
\(tan(angle)=\frac{sin(angle)}{cos(angle)}=\frac{y}{x}\)
Here is a pic that should help:
and
\( cos(\alpha+\beta)=cos\alpha cos\beta - sin\alpha sin\beta \\ \)
Now see if you can work it out yourself. :)
