Question

prove that :tan10 degree. cos20 degree. tan40 degree. tan50 degree. cosec 70 degree. sec80 degree. sin80 degree = 1

Answer 1

heya,

tan10° * cos 20° * tan40° * tan50° * cosec70° * sec80° * sin80°


now,

tan10° * cos 20° * tan40° * tan50° * cosec70° * (1/cos80° * sin80°)

tan10° * tan80° * tan40° * tan50° * cos20° * cosec(90 - 20)°

tan10° * tan(90 - 10)° * tan(90 - 50)° * tan50° * cos20° * sec20°

(tan10° * cot10°) * (cot50° * tan50°) * (cos20° * 1/cos20°)

(tan10° * 1/tan10°) * (tan50° * 1/tan50°) * 1

1 * 1 * 1

1