Le 4 mai 2021, la plateforme Yahoo Questions/Réponses fermera. Elle est désormais accessible en mode lecture seule. Aucune modification ne sera apportée aux autres sites ou services Yahoo, ni à votre compte Yahoo. Vous trouverez plus d’informations sur l'arrêt de Yahoo Questions/Réponses et sur le téléchargement de vos données sur cette page d'aide.

Jim W
Lv 7
Jim W a posé la question dans Science & MathematicsMathematics · il y a 3 ans

Which function do I need to use to calculate the opposite side of a triangle when the angle is known and the hypotenuse?

My trig is quite old like in the 60's and I do not usually need higher math functions at home or work. Thanks very much. the angle is 1.2 degrees.

1 réponse

Pertinence
  • ?
    Lv 7
    il y a 3 ans
    Réponse favorite

    sin(1.2°) = opposite/hypotenuse

    Old Mnemonic “soak a toe”

    SOH CAH TOA

    sine = opposite/hypotenuse

    cosine = adjacent/hypotenuse

    tangent = opposite/adjacent

    A modern formulation is in terms of coordinates on the unit circle where x^2+y^2 = 1

    a point (x,y) has a ray from (0,0) going through it which makes an angle theta measured counter clockwise from the postive x axis. Thus (x,y) = (cos(theta),sin(theta)). Many identities including sin^2(t) + cos^2(t) = 1 are easily seen or derived. For example: signs of functions in Q1 to Q4, negative angles, complementary and supplementary angles. Also special values in degrees or radians.

    If you define sine and cosine in terms of complex exponentials based on Euler’s identity, then addition, subtraction, double angle, half angle identities are almost immediate without referring to geometry at all.

Vous avez d’autres questions ? Pour obtenir des réponses, posez vos questions dès maintenant.