Check whether the result is true or false COS A =( a square + b square ) ÷ 2ab , - Maths - Introduction to Trigonometry

Question

Check whether the result is true or false COS A =( a square + b
square ) ÷ 2ab , where a & b are two distinct numbers
such that ab> 0

indermani.thapa · Accepted Answer

cosA=a2+b2-2ab+2ab2ab=a-b2+2ab2ab=a-b22ab+2ab2ab=a-b22ab+1Since, a-b2>0 and ab>0So, cosA=a-b22ab+1>1, which is not possible as maximum value of cosA is 1
Hence, it is false

Check whether the result is true or false COS A =( a square + b square ) ÷ 2ab , where a & b are two distinct numbers such that ab> 0