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

User DbJones
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1 Answer

4 votes

Answer:

90 degrees

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

User Ali Azimoshan
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5.5k points