Video narration
Ei sirita kotota khara, ar er uchchota na mepe, shudhu kon dekhe ki ta jana jay? Sirir pash theke dekhle, tar unchu howa, samne egiye jawa ar dhalu dik mile ekti right triangle, orthat samokoni tribhuj hoy. Kharabhav tokhon rohossho noy; eti kon ar bahugulor shomporko. Ekti kon beche nile sine, cosine, ebong tangent sei koner songe bahugulor onupat dekhay. Kon bahu jana, ar konti ber korte hobe, tar opor shothik onupat nirvor kore. Trigonometry odbhut sutro mukhosto kora noy. Eti kon ar ekti jana doirghyo byabohar kore ojana doirghyo ber korar poddhoti. Dhorun, sirir dhalu kon ebong matir opor tar durotto jana ache. Tangent byabohar kore uchchota hishab kora jay, karon eti konke ullombho otha ar onubhumik durotter onupate jukto kore. Ei shurut a somokoni tribhuj o mapa jay emon shomporker; puro Trigonometry aro bistrito. Tahole uttorti ki? Kon eka noy, ekti trikonmitik onupat, kon ar porichito doirghyoke jukto kore, sirir ojana uchchota janay.