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Show that the Tangent of an Angle Between the Lines X a + Y B = 1 and X a − Y B = 1 is 2 a B a 2 − B 2

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प्रश्न

Show that the tangent of an angle between the lines \[\frac{x}{a} + \frac{y}{b} = 1 \text { and } \frac{x}{a} - \frac{y}{b} = 1\text {  is } \frac{2ab}{a^2 - b^2}\].

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उत्तर

We have

\[\frac{x}{a} + \frac{y}{b} = 1 \text { and } \frac{x}{a} - \frac{y}{b} = 1\]

\[ \Rightarrow \frac{y}{b} = - \frac{x}{a} + 1 \text { and } \frac{y}{b} = \frac{x}{a} - 1\]

\[ \Rightarrow y = - \frac{b}{a}x + b \text { and} y = \frac{b}{a} - b\]

The slopes of the two lines are \[- \frac{b}{a}\text {  and } \frac{b}{a}\]

Now, the tangent of an angle between the lines is given by

\[\frac{\frac{b}{a} + \frac{b}{a}}{1 - \frac{b}{a} \times \frac{b}{a}}\]

\[ = \frac{\frac{2b}{a}}{\frac{a^2 - b^2}{a^2}}\]

\[ = \frac{2ab}{a^2 - b^2}\]

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अध्याय 23: The straight lines - Exercise 23.13 [पृष्ठ ९९]

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आर.डी. शर्मा Mathematics [English] Class 11
अध्याय 23 The straight lines
Exercise 23.13 | Q 10 | पृष्ठ ९९

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