using a double angle formula? What is her answer? 46. Demonstrate that the double angle formula for sin2x is derived from the compound angle formula for sin(a +b). 47. Prove that 1−tan2x 1+tan2x =cos2x is an identity. 48. Prove that sinx +sinxcot2x =secx is an identity. 49. Solve tan(x) =−1 where 0 ≤x ≤2π. a) How many solutions are ...

*Double angle and half angle identities are very important in simplification of trigonometric functions and assist in performing complex calculations with ease. Find the exact value of trig expressions, evaluate trig equations using the double and half angle formula, verify and prove the identities using the worksheets here.*Trigonometry Chapter 5 Lecture Notes Section 5.1 Fundamental Identities I. Negative-Angle Identities ... Using a Half-Angle Identity to Find an Exact Value You stumble upon an angle of the chair that is too small to have two easily solvable angles add up to it. You can't use the double angle formula anymore. But you can use the half angle formula that your favorite math teacher taught you! Your protractor tells you that the angle measures out to be 15 degrees. You should find the tangent of this ...