Question

If a = 4, b = 5 and sin A = 4/5 find angle B​

Answer 1

Answer:

angle B = 90°

Step-by-step explanation:

it is given that:

a = 4 , b = 5 and sin A = 4/5

using sine rule:

sin A/ a = sin B / b = sin C /c = R

where R is circumradius

consider a = 4 , b = 5 and sin A = 4/5 values and substitute in

sin A/ a = sin B / b

(4/5) / 4 = sin B / 5

(4/4)(1/5) = (sin B)(1/5)

sin B = 1

so sin 90 = 1

B = 90°

angle of B is 90 degrees

Answer 2

Answer:

The value of ∠B is 90 °

Step-by-step explanation:

• In context to the given question we have to find the the angle B

• Given that:

1. a = 4 ,
2. b = 5
3. sin A = 4/5

• TO FIND :

1. Angle B

Solution :

⇒ we know that:

⇒ using sine rule:

⇒ (sin A/ a ) = (sin B / b) = (sin C /c) = R

⇒ where R is circumradius

⇒ By putting the value of a , b and sin A

⇒ we get,

⇒ sin A/ a = sin B / b

⇒ (4/5) / 4 = sin B / 5

⇒ 4/20 = (sin B)(1/5)

⇒ 1/5= (sin B)(1/5)

⇒sin B = 1

We know that,

sin 90° = 1

B = 90°

∠B is 90 °