Q9 of 115 Page 8

If two straight lines are perpendicular to the same line, prove that they are parallel to each other.

Given m and l perpendicular to t

∠1 = ∠2 = 90^o

Since,

l and m are two lines and t is transversal and the corresponding angles are equal.

Therefore,

l ‖ m

Hence, proved

In Fig 8.111, state which lines are parallel and why?

In Fig 8.112, if l||m, n||p and ∠1 =85°, find ∠2.

Prove that the two arms of an angle are perpendicular to the two arms of another angle, then the angles are either equal or supplementary.

In Fig 8.113, lines AB and CD are parallel and P is any point as shown in the figure. Show that ∠ABP +∠CDP = ∠DPB.