Question

If sinA = `(3)/(5)`, find cosA and tanA.

Answer 1

sinA = `(3)/(5) = "Perpendicular"/"Hypotenuse"`

By Pythagoras theorem, we have
⇒ (Hypotenuse)² = (Perpendicular)² + (Base)²
⇒ (Base)2 = (Hypotenuse)² - (Perpendicular)²
⇒ (Base) = `sqrt(("Hypotenuse")^2 - ("Perpendicular")^2` 
⇒ (Base)
= `sqrt(5^2 - 3^2)`
= `sqrt(25 - 9)`
= `sqrt(16)`
= 4

cos A = `"Base"/"Hypotenuse" = (4)/(5)`

tan A = `"Perpendicular"/"Base" = (3)/(4)`.