Question

in triangle abc BC barabar CA and barabar 40 degree find the largest side of triangle ABC​

Answer 1

Answer:

In triangle ABC, if angle A = 40 and angle B = 60, then what is the longest side of ABC?

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7 Answers



Ved Prakash Sharma

Answered October 25, 2020 · Author has 9.2K answers and 4.9M answer views

Angle C =180°-(40°+60°) =80°. , longest side is c as angle C is the largest angle.

By sine rule:-

a/sinA. = b/sinB = c/sinC.

or, a/sin 40° = b/sin 60° = c/sin80°.

Now, a/sin40° = c/sin80°.

or, c = a.sin80°/sin 40° = a.(2.sin 40°.cos40°)/sin40°. = 2a.cos40°.

or, c = 2a.cos 40°. …………………(1)

Also , b/sin60° = c/sin80°.

or, c = b.sin 80°/sin 60°. = (2b/√3).sin 80°…………….(2)

From eqn. (1) and (2).

Longest side c. = 2a.cos40° or , (2b/√3).sin 80°