In ∆ABC if AB = 6 cm , BC = 8cm, AC = 10 cm then value of ∠B is ________​

Question

In ∆ABC if AB = 6 cm , BC = 8cm, AC = 10 cm then value of ∠B is ________​

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Thành Đạt 1 month 2021-08-06T05:10:01+00:00 1 Answers 2 views 0

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    2021-08-06T05:11:38+00:00

    Answer:

    90 degrees

    Step-by-step explanation:

    B is the corner and angle opposite of the side AC.

    so, AC is becoming side c, and the other two are a and b (it does not matter which is which).

    we use the enhanced Pythagoras formula for general triangles

    c² = a² + b² – 2ab×cos(C)

    in our example the angle C is named B.

    but other than that we simply calculate

    10² = 6² + 8² – 2×6×8×cos(B)

    100 = 36 + 64 – 96×cos(B)

    100 = 100 – 96×cos(B)

    0 = -96×cos(B)

    cos(B) = 0

    =>

    B = 90 degrees

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