Question

What is the solution if the equation n(n+1)/2=21​

Answer 1

Answer:

In △ABC AB=AC

⇒∠B=∠C (Angles opposite to equal sides are equal)

Now using angle sum property

∠A+∠B+∠C=180

∘

⇒80

∘

+∠C+∠C=180

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⇒2∠C=180

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−80

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⇒∠C=

2

100

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=50

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now ∠C+∠x=180

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(Angles made on straight line (AC) are supplementary)

⇒50

∘

+∠x=180

∘

⇒∠x=180

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−50

∘

=130

∘

@ARSH

insta@_arsh_deep_29

Answer 2

Answer: Refer to the image