In the given figure, AB = AC, D is a point on AC and E an AB such that AD = ED = EC = BC, The ratio \(\angle{BAC} : \angle{ABC} =\)
1 : 3
AD = DE = EC = BC (given)
∠DAE=∠AED=x(say)
∴∠EDC=2x... (exteriar angle theorem)
∴∠ECD=2x... (ED = EC, base angles of an isosceles Δ)
∴∠CEB=x+2x (exteriar angle theorem)
= 3x
∴∠ABC=∠CEB=3x (base angles of an isosceles Δ)
∠BAC:∠ABC=x:3x
= 1 : 3
Hence(B)