How do you use the fundamental identities to prove other identities? Trigonometry Trigonometric Identities and Equations Fundamental Identities 1 Answer Kevin B. Feb 22, 2015 Divide the fundamental identity # sin^2x + cos^2x = 1# by #sin^2x# or #cos^2x# to derive the other two: #sin^2x/sin^2x + cos^2x/sin^2x = 1/sin^2x# #1 + cot^2x = csc^2x# #sin^2x/cos^2x + cos^2x/cos^2x = 1/cos^2x# #tan^2x + 1 = sec^2x# 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? 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)#? How do you simplify #(cos4x-cos2x)/(sin 4x + sin 2x)#? See all questions in Fundamental Identities Impact of this question 10822 views around the world You can reuse this answer Creative Commons License