Question

if sintheta=4/5then the value of cos
theta​

Answer 1

answer= 3/5

explaination=

sinθ = opp/hypo

= 4k/5k

by pythagorean triplets 3rd side is 3k

so, adj=3k

hypo= 5k

opp= 4k

so, cosθ = adj/hypo

= 3k/5k

=3/5

Answer 2

Answer:

cosФ = 3/5

Step-by-step explanation:

Given that,

sinФ = 4/5                    (Note: Here I’ve considered theeta as Ф)

cosФ = ?

we know that,

sinФ = $\frac{opposite side}{hypotenuse}$ & cosФ = $\frac{Adjacentside}{hypotenuse}$

⇒ sinФ = $\frac{opposite side}{hypotenuse} = \frac{4}{5}$         (∵ given)

Opposite side = 4 & hypotenuse = 5

Let, adjacent side = x

In a right angled triangle according to the Pythagorean’s theorem,

(Hypotenuse)² = (opposite side)² + (adjacent side)²

⇒ (5)² = (4)² + (x)²

⇒ 25 = 16 + x²

⇒ x² = 25 - 16

⇒ x² = 9

⇒ x = √9 = 3

adjacent side (x) = 3

So, cosФ = $\frac{adjacent side}{hypotenuse} = \frac{3}{5}$

∴ cosФ = 3/5

HOPE THIS WOULD BE HELPFUL FOR YOU