Question

can you plz answer fast​

Answer 1

Answer:

Given, angle A = 2*angle B,

Apply sine rule i.e.

a/(Sin A)= b/(Sin B)= c/(Sin c)

Take first 2 entities as we were given information about A and B. Also,

substitute A = 2B

Now,we have

a/(Sin 2B) = b/(Sin B)

Sin 28 = 2 "(Sin B)(Cos B)

Substituting this in above equation.Thus,

Sin B gets cancelled because B is not equal to zero(because it is a triangle).By extension Sin B is not equal to zero.

We get.

a/(2 Cos B) = b [now apply cosine rule] Cos B = (a^2 + c^2 - b^2)/2*a*c

Substituting we get the result,

a^2 = b[b+c)=b^2+b*c BC 2 = AC^2 + AC AB

hope it helps you

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