with out using calculator find the valu of cos (105)
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Using identity
Cos(A+B) = cosAcosB -sinAsinB
Cos(60+45) = cos60cos45 -sin60sin45
Cos(105) = 1/2 × 1/√2 - √3/2 × 1/√2
Cos(105) = 1/2√2 - √3/2√2
Cos(105) = 1-√3/2√2
Cos(A+B) = cosAcosB -sinAsinB
Cos(60+45) = cos60cos45 -sin60sin45
Cos(105) = 1/2 × 1/√2 - √3/2 × 1/√2
Cos(105) = 1/2√2 - √3/2√2
Cos(105) = 1-√3/2√2
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