Question 19 [Assertion Reasoning] - CBSE Class 12 Sample Paper for 2023 Boards - Solutions of Sample Papers and Past Year Papers - for Class 12 Boards
Last updated at April 16, 2024 by Teachoo
Assertion (A):
The domain of the function sec
-1
2x is (-∞,1/2]∪[1/2,∞ )
Reason (R
): sec
-1
(-2)=-π/4
In the following questions, a statement of assertion (A) is followed by a statement of Reason (R). Choose the correct answer out of the following choices.
(a) Both A and R are true and R is the correct explanation of A.
(b) Both A and R are true but R is not the correct explanation of A.
Question 19 Assertion (A): The domain of the function γπ ππγ^(β1) 2π₯ ππ (ββ,1/2]βͺ[1/2,β ) Reason (R): γπ ππγ^(β1) (β2)=βπ/4 In the following questions, a statement of assertion (A) is followed by a statement of Reason (R). Choose the correct answer out of the following choices. (a) Both A and R are true and R is the correct explanation of A. (b) Both A and R are true but R is not the correct explanation of A. (c) A is true but R is false. (d) A is false but R is true.
Checking Assertion
Assertion (A): The domain of function γπ ππγ^(β1) 2π₯ ππ (ββ,1/2]βͺ[1/2,β )
We know that
Domain of γπ ππγ^(β1) ΞΈ ππ (ββ,1]βͺ[1,β )
Thus,
ββ<ΞΈβ€1 and 1β€ ΞΈ<β
Putting ΞΈ = 2x
ββ<2π₯β€1 and 1β€2π₯<β
Dividing both sides by 2
ββ/2<2π₯/2β€1/2 and 1/2β€2π₯/2<β/2
ββ<πβ€π/π and π/πβ€π<β
Thus,
Domain of γπ ππγ^(β1) 2π₯ ππ (ββ,π/π]βͺ[π/π,β )
Thus, Assertion is true
Checking Reason
Reason (R): γπ ππγ^(β1) (β2)=βπ/4
Let y = secβ1 (β2)
y = πβ secβ1 (2)
y = π β π/3
y = ππ /π
Since Range of secβ1 is [0, Ο] β {π/2}
Hence, Principal Value is ππ /π
Thus, Reasoning is false
So,
Assertion is true
Reasoning is false
So, the correct answer is (c)
Made by
Davneet Singh
Davneet Singh has done his B.Tech from Indian Institute of Technology, Kanpur. He has been teaching from the past 14 years. He provides courses for Maths, Science and Computer Science at Teachoo
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