Find the angle between the two planes given by the equations 3x + 4y – 5z = 5 and 2x + 5y + 4z = 12.

Answer (Detailed Solution Below)

Option 3 :
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NDA 01/2025: English Subject Test
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Detailed Solution

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CONCEPT:

Let A1x + B1y + C1z + D1 = 0 and A2x + B2y + C2 z + D2 = 0 are the equations of two planes aligned at an angle θ where A1, B1, Cand A2, B2, C2 are the direction ratios of the normal to the planes, then the cosine of the angle between the two planes is given by:

CALCULATION

Given planes are 3x + 4y – 5z = 5 and 2x + 5y + 4z = 12.

Angle between angles 

⇒ 

⇒ 

⇒ 

⇒ 

∴ 

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