Q2 of 21 Page 113

In right angled ΔTSU, TS = 5, S = 900, SU =12 then find sin T, cos T, tan T. Similarly find sin U, cos U, tan U.

For any right-angled triangle,

sinθ = Opposite side /Hypotenuse


cosθ = Adjacent side/Hypotenuse


tanθ = sinθ/cosθ


= Opposite side /Adjacent side


cotθ = 1/tanθ


= Adjacent side/Opposite side


secθ = 1/cosθ


= Hypotenuse/Adjacent side


cosecθ = 1/sinθ


= Hypotenuse/Opposite side


In the given triangle let us understand, the Opposite side and Adjacent sides.


So for T,


Opposite side= US =12


Adjacent side = TS = 5


So for U,


Opposite side = TS = 5


Adjacent side = US = 12


In general, for the side Opposite side to the 90° angle is the hypotenuse.


So for Δ TSU,


By Pythagoras Theorem


Hypotenuse2 = Opposite side2 + Adjacent2


= 122 + 52


= 144 + 25


= 169


Hypotenuse = 13


(i) sin T = Opposite side/Hypotenuse


= US/TU


= 12/13


(ii) cos T= Adjacent side/Hypotenuse


= TS/TU


= 5/13


(iii) tan T = sinθ/cosθ


= Opposite side/Adjacent side


= US/TS


= 12/5


(i) sin U = Opposite side/Hypotenuse


= TS/TU


= 5/13


(ii) cos T= Adjacent side/Hypotenuse


= US/TU


= 12/13


(iii) tan T = sinθ/cosθ


= Opposite side /Adjacent side


= TS/US


= 5/12


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