D.

we need to know the gradient of line m2: to find out whether m1*m2 = -1.

This info is available in either of the options so C.

GmatKiss wrote:If lines m1 and m2 intersect in the coordinate plane, and m1 is given by y = 2x + 3, do they form a right angle at their point of intersection?

(1) m2 is given by y = -x/3 + 1
(2) Points (3,0) and (-6, 3) lie on line m2

GmatKiss wrote:If lines m1 and m2 intersect in the coordinate plane, and m1 is given by y = 2x + 3, do they form a right angle at their point of intersection?

(1) m2 is given by y = -x/3 + 1
(2) Points (3,0) and (-6, 3) lie on line m2

We already have the slope of line 1 . All we need is the slope of line 2. (As if m1 * m2 = -1 then lines are perpendicular)

We can find it by using both equation 1 and equation 2.

Ans D

if we have t he equation of another line of we can atleast form the equation ( in option (2) two co-ordinates are given) we can find the relation between two lines.

We are given the equation of the line m1, also note this line is "linear".

Option (1) gives us an equation for another "linear" line. so we could figure this question out with this choice alone. therefore, this choice is sufficient alone.

Option (2) gives us 2 points on a line. In this choice, we are not informed whether m2 is linear or not (m2 could be a parabola in which these points reside, it could be a straight line, or any other of the infinite possibilities that could connect these 2 points). Remember that we need at least 3 points along a line to determine whether the line is linear. This choice is insufficient by itself.

Therefore, given these two options, the answer is A

maihuna wrote:D.

we need to know the gradient of line m2: to find out whether m1*m2 = -1.

This info is available in either of the options so C.

GmatKiss wrote:If lines m1 and m2 intersect in the coordinate plane, and m1 is given by y = 2x + 3, do they form a right angle at their point of intersection?

(1) m2 is given by y = -x/3 + 1
(2) Points (3,0) and (-6, 3) lie on line m2