the x87 was the coprocessor for 386 level cpu generation that was integrated in the 386DX chips, adding a co-proc to the SX chips allowed for 'serious' improvement in mathematical power. They still existed at the 486 level but were totally phased out for Pentiums.
So even though there was an x87, you're still talking out yer arse.
x87 got absorbed into x86 long ago, and the x86 internal architecture has been becoming less and less cisc for years, whilst still maintaining instructional compatability.
/me remembers when his father bought a co-proc...