Hi , can anyone help please? 7) Given triangle ABC alongside
a) Determine an expression for Angle A in terms of B and C
the answer here is A = 180° - B - C

I'm just not sure how to answer b!
b) Hence, prove that cos A = sin B sin C - cos B cos C ​

add the table and i will answer correctly

step-by-step explanation:

ca = ec

cpctc makes it so that corresponding parts of the triangle you proved to be equal are equal, the other options aren't part of the part of the triangles you proved to be equal.

idk

step-by-step explanation:

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