In a triangle ABC,AB=10 cm and AC=5 cm. The area

estroishave4

estroishave4

Answered question

2022-04-21

In a triangle ABC,AB=10 cm and AC=5 cm. The area is 15 cm2 and the angle BAC is equal to θ
Give two possible values of θ
I was able to find one of the values of cosθ which is 0.8 but how can I get a second value for cosθ?

Answer & Explanation

amisayq6t

amisayq6t

Beginner2022-04-22Added 18 answers

The area of the triangle will be equal to
(AB)(AC)sinθ2
meaning that sinθ=0.6 , as you probably found. This means that
cos2θ=1sin2θ=0.64
and
cosθ=±0.8
The positive value corresponds to θ an acute angle, and then negative value corresponds to obtuse θ.

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