cos²A + cos²B + cos²C = 1 - 2cosAcosBcosC
Therefore cos²A + cos²B + cos²C + 2cosAcosBcosC = 1
cos2A+cos2B+cos2C+2cosAcosBcosC
where ABC is a triangle
cos²A + cos²B + cos²C = 1 - 2cosAcosBcosC
Therefore cos²A + cos²B + cos²C + 2cosAcosBcosC = 1
this question did not appear properly in the test.............. i dint understnd the question as unnecessary terms like p and square brackets were put in the question.............