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Introduction to Trigonometry
CH08 Question Bank
CBSE_CH08_QUESTION_BANK
Grade 10
Question:
Assertion (A): The value of $\tan 90^\circ$ is not defined. Reason (R): $\tan\theta=\dfrac{\sin\theta}{\cos\theta}$, and $\cos 90^\circ=0$.
Both Assertion (A) and Reason (R) are true, and R is the correct explanation of A. Both Assertion (A) and Reason (R) are true, but R is NOT the correct explanation of A. Assertion (A) is true, but Reason (R) is false. Assertion (A) is false, but Reason (R) is true.
Step-by-Step Solution
Key Concept: Division by zero makes the ratio undefined at this specific angle.
Since $\tan90^\circ$ would require dividing by $\cos90^\circ=0$, it is indeed not defined — A is true. [0.5 Mark]
R correctly identifies both the quotient relationship and the reason ($\cos90^\circ=0$) that causes the expression to be undefined, so R correctly explains A. [0.5 Mark]
Correct Answer:Both Assertion (A) and Reason (R) are true, and R is the correct explanation of A.
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