MHT CET202313 May 2023Evening ShiftMathematicsThree Dimensional GeometryActual
A tetrahedron has vertices at P (2,1,3) , Q (-1,1,2), R (1,2,1) and O (0,0,0) , then angle between the faces OPQ and PQR is
Options
- A⁻¹ ( 5 7 59 )
- B⁻¹ ( 25 59 35 )
- C⁻¹ ( 5 413 )
- D⁻¹ ( 25 59 35 )
Correct answer
D. ⁻¹ ( 25 59 35 )
Step-by-step solution
aligned O P O Q & = | array ccc i & j & k 2 & 1 & 3 -1 & 1 & 2 array | & =- i -7 j +3 k aligned aligned P Q P R & = | array ccc i & j & k -3 & 0 & -1 -1 & 1 & -2 array | & = i -5 j -3 k aligned Angle between the faces OPQ and PQR is = (- i -7 j +3 k ) ( i -5 j -3 k ) (-1)^2+(-7)^2+3^2 1^2+(-5)^2+(-3)^2 = -1+35-9 59 35 aligned & = 25 59 35 & = ⁻¹ ( 25 59 35 ) aligned