The sides BC,CA and AB of ΔABChave been produced to D ,E and respectively ∠BAE+∠CBF+∠ACD=?.
(a)240∘ (b)300∘ (c)320∘ (d)360∘
ANSWER:
(d) 360∘
We have :∠1+∠BAE=180∘ ...i
∠2+∠CBF=180∘...iiand∠3+∠ACD=180∘ ...iii
Adding (i), (ii) and (iii), we get:∠1+∠2+∠3+∠BAE+∠CBF+∠ACD=540∘
⇒180∘+∠BAE+∠CBF+∠ACD=540∘∵∠1+∠2+∠3=180∘⇒∠BAE+∠CBF+∠ACD=360∘