If the angle between the planes r → . ( m i ^ − j ^ + 2 k ^ ) + 3 = 0 and r → . ( 2 i ^ − m j ^ − i ^ ) − 5 = 0 is π 3 then m =

Question

If the angle between the planes r → . ( m i ^ − j ^ + 2 k ^ ) + 3 = 0 and r → . ( 2 i ^ − m j ^ − i ^ ) − 5 = 0 is π 3 then m =, 2, ± 3, 3, - 2

MARKS App · Accepted Answer

Angle between given planes is Cos θ = n - 1 ⋅ n - 2 n - 1 n - 2 ⇒ 1 2 = 2 m + m - 2 m 2 + 5 m 2 + 5 1 2 = 3 m - 2 m 2 + 5 ⇒ m 2 + 5 = ± 6 m - 4 ⇒ m 2 + 5 = 6 m - 4 , m 2 + 5 = - 6 m + 4 m 2 - 6 m + 9 = 0 , m 2 + 6 m + 1 = 0 m - 3 2 = 0 m = 3

Search any question & find its solution

Looking for more such questions to practice?