Abstract: The invention “Trio-meter”is a multipurpose instrument by using—“Multi-slotted link sliding assembly mechanism”—for triangle solutions including Pythagoras theorem' as a ready reckoner (FIG. II). Useful instrument with marker block attachment to draw and measure straight lines, lengths, arcs, semi circles, circles, bicircles, tricircles, parallelograms, rhombuses, trapezoids, parallellines and triangles with fractional and accurate measurements easily and quickly (FIG. III to VIII). The novel instrument with tri-sector attachments, trisects an angle and multiplies an angle into double, triple & quadruple as well as reduces an angle in to two-third half, one third and quarter fractionally and accurately (FIG. IX).