Question

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

Answer 1

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