Q. 34.3( 240 Votes )
If sin
calculate Cos A and tan A
Answer :
Let ΔABC be a right-angled triangle, right-angled at point B
Given that:
As we know trigonometrical ratios give ratio between sides of right angled triangle instead of their actual values. So from sin A we get the ratio of Perpendicular and Hypotenuse of the triangle. Now as we don't know the exact value let Perpendicular = 3 k and Hypotenuse = 4 k
According to Pythagoras theorem: (Hypotenuse)2 = (Base)2 + (Perpendicular)2Applying Pythagoras theorem in ΔABC, we obtain
AC2 = AB2 + BC2
(4k)2 = AB2 + (3k)2
16k2 - 9k2 = AB2
7k2 = AB2
Cos A =
= =

Tan A =
= =
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