We need to use cosine law in order to find all the angles if we are given with all the sides.
To find angle A formula is:
To find angle B, we will use formula:
To find angle C, we can use formula:
but we can also use property
if we already know values of angle A and angle B.
Suppose, a = 15 cm, b = 10 cm and c = 17 cm. Our formula is
In order to find
, we use formula
Cosine law can also be used to find side of triangle if we know two other sides of triangle and angle between the two known sides is also known. For example, if we have
, b = 20 cm and c = 25 cm then we can use formula
to find side a.
cm
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