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Question: If the coordinates of point A, B, C are (–1, 3, 2), (2, 3, 5) and (3, 5, –2) respectively then ang...

If the coordinates of point A, B, C are (–1, 3, 2),
(2, 3, 5) and (3, 5, –2) respectively then angle A is

A

00

B

450

C

600

D

900

Answer

900

Explanation

Solution

D.R's of AB are 3, 0, 3

D.R's of AC are 4, 2, –4

\ cos A = (3)(4)+(0)(2)+3(4)9+916+4+16\frac{(3)(4) + (0)(2) + 3( - 4)}{\sqrt{9 + 9}\sqrt{16 + 4 + 16}}

cos A = 0

\ ŠA = 900