What is sin(-theta) in terms of sintheta? Trigonometry Trigonometric Identities and Equations Fundamental Identities 1 Answer Lucy Apr 28, 2018 sin(-theta) = -sintheta Explanation: -theta means that your angle is in the fourth quadrant for sine, it is negative in the fourth quadrant SO sin(-theta) = -sintheta Answer link Related questions How do you use the fundamental trigonometric identities to determine the simplified form of the... How do you apply the fundamental identities to values of theta and show that they are true? How do you use the fundamental identities to prove other identities? What are even and odd functions? Is sine, cosine, tangent functions odd or even? How do you simplify sec xcos (frac{\pi}{2} - x )? If csc z = \frac{17}{8} and cos z= - \frac{15}{17}, then how do you find cot z? How do you simplify \frac{\sin^4 \theta - \cos^4 \theta}{\sin^2 \theta - \cos^2 \theta} using... How do you prove that tangent is an odd function? How do you prove that sec(pi/3)tan(pi/3)=2sqrt(3)? See all questions in Fundamental Identities Impact of this question 16082 views around the world You can reuse this answer Creative Commons License