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Solve the following trigonometric expression: sec2A+(csc2A−1)−(1+tan2A)−cot2A=_____
1
sec² A
0
cot² A
0
Use the basic identities sec2A−tan2A=1 and csc2A−cot2A=1. The expression simplifies to (1)+(cot2A)−(1+tan2A)−cot2A, which reduces quickly.
An algebraic expression containing trigonometric functions: sec2A+(csc2A−1)−(1+tan2A)−cot2A
sec2A=1+tan2A,csc2A=1+cot2A
Use the basic identities sec2A−tan2A=1 and csc2A−cot2A=1. The expression simplifies to (1)+(cot2A)−(1+tan2A)−cot2A, which reduces quickly.
A common mistake is incorrectly distributing the negative sign across the terms inside the parentheses or forgetting that csc2A−1=cot2A.
Simplify using identities
We know that csc2A−1=cot2A and 1+tan2A=sec2A.
csc2A−1=cot2A,1+tan2A=sec2A
Substitute and rearrange
Substitute these identities into the original expression: sec2A+cot2A−sec2A−cot2A.
sec2A+cot2A−sec2A−cot2A
Final cancellation
Group the terms to see that they cancel out: (sec2A−sec2A)+(cot2A−cot2A)=0+0=0.
0
C is correct because after simplifying the expression using fundamental trigonometric identities, all terms cancel out to result in 0.
Trigonometric simplification is frequently tested in competitive exams; always look for standard identity patterns like 1+tan2θ or cosec2θ−1 first.