Question

In an isosceles triangle abc ab=ac and bc is produced to d such that angle acd = 100

Answer 1

$\huge{ \tt{♕︎ sᴏℓᴜᴛɪᴏɴ ♕︎}}$

➨We have ,

→ ZACD + ZACB = 180 ° [ Linear Pair ]

→ 100 ° + ZACB = 180 °

→ ZACB = 180 ° - 100 °

→ ZACB = 80 °

➨From ( i ) & ( ii ) ,

➨ We get

➨ Angle ZABC = Angle ZACB = 80 °

➨Now ,

→ ZABC + ZACB + ZA = 180º .... [ Sum of the 3 interior angles of a triangle is 180° ]

→ Substituting the values of ZABC & ZACB ,

➨ We get

→ 80 ° + 80 ° + A = 180 °

→ 160 ° + ZA = 180 °

→ ZA = 180 ° - 160 °

→ ZA = 20 °

Thus , the measure of Angle ‘A’ is 20 °