NIMCET 2021 — Mathematics PYQ
NIMCET | Mathematics | 2021The area of the region bounded by the X-axis and the curves and is

The area of the region bounded by the X-axis and the curves y=tanx,−π/3≤x≤π/3 and y=cotx,π/6≤x≤3π/2 is
−21log2
21log2
log2
None of these
(Correct Answer)None of these
Area Calculation
The area of the region bounded by the X-axis and the curves y=tanx,−3π≤x≤3π and y=cotx,6π≤x≤23π is to be determined.
Step 1: Analyze the functions and intervals
The function y=tanx is considered in the interval [−3π,3π]. In this interval, tanx is negative for x∈[−3π,0) and positive for x∈(0,3π]. The function y=cotx is considered in the interval [6π,23π]. In this interval, cotx is positive for x∈[6π,2π) and negative for x∈(2π,23π].
Step 2: Calculate the area under y=tanx
The area A1 under y=tanx from x=−3π to x=3π is given by the integral: A1=∫−3π3π∣tanx∣dx. Due to the symmetry of ∣tanx∣ about the y-axis, this can be written as: A1=2∫03πtanxdx. The integral of tanx is −log∣cosx∣. A1=2[−log∣cosx∣]03π=2(−log(cos(3π))−(−log(cos(0)))). A1=2(−log(21)+log(1))=2(−log(21)+0)=−2log(21). Using the property log(ba)=loga−logb and log(ab)=bloga: A1=−2(log1−log2)=−2(0−log2)=2log2.
Step 3: Calculate the area under y=cotx
The area A2 under y=cotx from x=6π to x=23π is given by the integral: A2=∫6π23π∣cotx∣dx. This integral needs to be split due to the change in sign of cotx at x=2π: A2=∫6π2πcotxdx+∫2π23π∣cotx∣dx. The integral of cotx is log∣sinx∣. For the first part: ∫6π2πcotxdx=[log∣sinx∣]6π2π=log(sin(2π))−log(sin(6π))=log(1)−log(21)=0−log(21)=log2. For the second part, cotx is negative in (2π,23π), so ∣cotx∣=−cotx: ∫2π23π−cotxdx=−[log∣sinx∣]2π23π=−(log∣sin(23π)∣−log∣sin(2π)∣)=−(log∣−1∣−log∣1∣)=−(log1−log1)=0. Therefore, A2=log2+0=log2.
Step 4: Combine the areas
The total area is the sum of A1 and A2: Total Area =A1+A2=2log2+log2=3log2.
Final Answer
The final answer is None of these.
Area Calculation
The area of the region bounded by the X-axis and the curves y=tanx,−3π≤x≤3π and y=cotx,6π≤x≤23π is to be determined.
Step 1: Analyze the functions and intervals
The function y=tanx is considered in the interval [−3π,3π]. In this interval, tanx is negative for x∈[−3π,0) and positive for x∈(0,3π]. The function y=cotx is considered in the interval [6π,23π]. In this interval, cotx is positive for x∈[6π,2π) and negative for x∈(2π,23π].
Step 2: Calculate the area under y=tanx
The area A1 under y=tanx from x=−3π to x=3π is given by the integral: A1=∫−3π3π∣tanx∣dx. Due to the symmetry of ∣tanx∣ about the y-axis, this can be written as: A1=2∫03πtanxdx. The integral of tanx is −log∣cosx∣. A1=2[−log∣cosx∣]03π=2(−log(cos(3π))−(−log(cos(0)))). A1=2(−log(21)+log(1))=2(−log(21)+0)=−2log(21). Using the property log(ba)=loga−logb and log(ab)=bloga: A1=−2(log1−log2)=−2(0−log2)=2log2.
Step 3: Calculate the area under y=cotx
The area A2 under y=cotx from x=6π to x=23π is given by the integral: A2=∫6π23π∣cotx∣dx. This integral needs to be split due to the change in sign of cotx at x=2π: A2=∫6π2πcotxdx+∫2π23π∣cotx∣dx. The integral of cotx is log∣sinx∣. For the first part: ∫6π2πcotxdx=[log∣sinx∣]6π2π=log(sin(2π))−log(sin(6π))=log(1)−log(21)=0−log(21)=log2. For the second part, cotx is negative in (2π,23π), so ∣cotx∣=−cotx: ∫2π23π−cotxdx=−[log∣sinx∣]2π23π=−(log∣sin(23π)∣−log∣sin(2π)∣)=−(log∣−1∣−log∣1∣)=−(log1−log1)=0. Therefore, A2=log2+0=log2.
Step 4: Combine the areas
The total area is the sum of A1 and A2: Total Area =A1+A2=2log2+log2=3log2.
Final Answer
The final answer is None of these.
