Originally Posted by

**Macleef** **Please show me step by step solution!!! **

__Question 1:__

Determine whether the following pairs of planes are coincident, parallel and distinct or neither.

a) $\displaystyle x + 3y - z - 2 = 0$ and $\displaystyle 2x + 6y - 2z - 8 = 0$

**TEXTBOOK ANSWER:** parallel and distinct

I don't know how to put scalar equations into parametric equations...and how to find the direction vector...

-----------------

__Question 2:__

The angle between 2 planes is defined as the angle between their normals. Determine the angle (0 ≤ θ ≤ 90), to the nearest degree, between the given planes.

a) $\displaystyle 2x + 3y - z + 9 = 0$ and $\displaystyle x + 2y + 4 = 0$

**TEXTBOOK ANSWER:** 17 degrees

For #2, do you use the cross product?

sinθ = (|u x v|) / (|u||v|)

Again...for this question...I don't know how to put the scalar equation into parametric equation or find the direction vector..I know you use the algebraic cross product to find the normal vector, but I don't know what method to use to find the direction vector...I also know for a line, d = (d1, d2) and n = (-d2, d1)...

Thanks.