10th Class Mathematics Introduction to Trigonometry Question Bank Assertion and Reason MCQs - Introduction to Trigonometry

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    Directions: Each of these questions contains two statements: Assertion [A] and Reason [R]. Each of these questions also has four alternative choices, any one of which is the correct answer. You have to select one of the codes [a], [b], [c] and [d] given below.
    Assertion The equation \[{{\sec }^{2}}\theta =\frac{4xy}{{{\left( x+y \right)}^{2}}}\] is only possible when \[x=y\].
    Reason \[{{\sec }^{2}}\theta >1\]and therefore \[{{\left( x-y \right)}^{2}}<0\].

    A) A is true, R is true; R is a correct explanation for A.

    B) A is true, R is true; R is not a correct explanation for A.

    C) A is true; R is false.

    D) A is false; R is true.

    Correct Answer: A

    Solution :

    We know that,
                            \[{{\cos }^{2}}\theta \le 1\]
                \[{{\sec }^{2}}=\frac{4xy}{{{\left( x+y \right)}^{2}}}\ge 1\]
     \[\Rightarrow 4xy\ge {{\left( x+y \right)}^{2}}\]
     \[\Rightarrow {{\left( x-y \right)}^{2}}\le 0\]
     Assertion is true and Reason is true and is the correct explanation of Assertion.
     


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