Q23 of 115 Page 8

If, l, m, n are three lines such that l||m and n⊥ l, prove that n⊥ m.

Given that,

l ‖ m and n perpendicular to m

Since, l ‖ m and n intersects them at G and H respectively

Therefore,

∠1 = ∠2 (Corresponding angles)

But, ∠1 = 90^o as n is perpendicular to l

Therefore, ∠2 = 90^o

Hence, n is perpendicular to m.

In Fig 8.118, transversal l intersects two lines m and n, ∠4= 110° and ∠7 = 65°. Is m||n?

Which pair of lines in fig 8.119 are parallel? Given reasons

In Fig 8.120, arms BA and BC of ∠ABC are respectively parallel to arms ED and EF of ∠DEF. Prove that ∠ABC = ∠DEF.

In Fig 8.121, arms BA and BC of ∠ABC are respectively parallel to arms ED and EF of ∠DEF. Prove that ∠ABC + ∠DEF = 180°