Using Langranges mean value theorem for f(x)=cosx we get that |cosa-cosb| is less than or equal to=?A.|a+b|B.|a-b|C.|2a-b|D.|2a+b|

According to MVT given function is continuous and differentiable then, Derivative if f(c) equal to f(b)-f(a)/ b-a According to this cos b - cos a /b-a equal to -sin c Taking modules on both sides We get lcos a- cos bl equal to lb-al sinc which is less than or equal to la-blTherefore lcos a- cosbl is less or equal to la-bl