Q. If sinA=p and cosA=q :5.3.1 Write tanA in terms of p and q5.3.2 Simplify p4−q4 to a single trigonometric ratio
Trigonometric Identity:tanA=cosAsinAtanA=qp
Factoring Difference of Squares:p4−q4 can be factored as a difference of squares.(p2)2−(q2)2=(p2+q2)(p2−q2)
Pythagorean Identity: We know that sin2A+cos2A=1.So, p2+q2=1.
Substitution: Substitute 1 for p2+q2 in the factored form.(1)(p2−q2)
Simplify Using Pythagorean Identity: Now, we simplify p2−q2 using the Pythagorean identity.p2−q2=sin2A−cos2A
Double Angle Formula:sin2A−cos2A can be written as cos(2A) using the double angle formula for cosine.cos(2A)=cos2A−sin2ABut we need sin2A−cos2A, which is −cos(2A).
Final Simplification: So, p4−q4 simplifies to −cos(2A).
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