Math, asked by ziddiqueen65, 6 months ago

prove that the bisector of two adjacent supplementary angles include a right angle​

Answers

Answered by llAmyll
24

given

⠀⠀⠀⠀CE−→−CE→ is the bisector of ∠ACD and

⠀⠀⠀⠀⠀⠀⠀⠀⠀CF−→−CF→ is the bisector of ∠BCD

⠀⠀⠀To prove÷∠ECF = 90o

proof÷

From the figure we know that

∠ACD and ∠BCD form a linear pair of angles

⠀⠀⠀⠀⠀⠀⠀⠀⠀So we can write it as ⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀∠ACD + ∠BCD = 180o

We can also write it as

⠀⠀⠀⠀⠀⠀∠ACE + ∠ECD + ∠DCF + ∠FCB = 180o

⠀⠀⠀⠀⠀⠀⠀⠀From the figure we also know that

∠ACE = ∠ECD and ∠DCF = ∠FCB

⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀So it can be written as

⠀⠀⠀⠀⠀⠀∠ECD + ∠ECD + ∠DCF + ∠DCF = 180o

⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀

On further calculation we get

⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀2 ∠ECD + 2 ∠DCF = 180o

⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀

Taking out 2 as common we get

⠀⠀⠀⠀⠀⠀2 (∠ECD + ∠DCF) = 180o

⠀⠀⠀⠀⠀⠀⠀By division we get

⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀(∠ECD + ∠DCF) = 180/2

⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀∠ECD + ∠DCF = 90o

⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀

Therefore, it is proved that ∠ECF = 90o

Answered by itskittu
2

Answer:

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