Explanation: Since sin θ is negative, it can be in the third or fourth quadrant Drawing your right-angled triangle, place your θ in one of three corners. Your longest side will be 3 and the side opposite the θ will be -2. Finally, using Pythagoras theorem, your last side should be √ 5
Now, if your triangle was in the third quadrant, you would have cos θ = √ 5 − 3 since cosine is negative in the third quadrant But if your triangle was in the fourth quadrant, you would have cos θ = √ 5 3 since cosine is positive in the fourth quadrant
