Please explain the stereo of this rxn i didn't understand how cis and trans both are having same stereo

oxidation of olefine with MCPBA ( meta chloro perbenzoic acid ) is provided nacent oxygen it is attack to olefine from one side. so in cis olefine two methyls are same side to epox...

here concerted mechanism takes place so stereochemistry of reactant will be maintained in the product. so cis gives cis and trans gives trans product

Both are having different stereo...cis gives cis and trans give trans