What is the measure of angle A in the triangle below?

Solution:

From the figure,

AB = 18, BC = 9., ∠A = ?

Definition:

The sine x or sine theta can be defined as the ratio of the opposite side of a right triangle to its hypotenuse. Then, the sine formula is given by:

Sin α = Opposite side/ Hypotenuse

or

Sin α = Perpendicular/Hypotenuse.

Sin α = a/h.

Sinθ = opposite / hypotenuse

SinA = 9/18.

SinA = 1/2.

We know that

SinA = Sin30°.

∠A = 30°.

Therefore, ∠A = 30°.

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What is the measure of angle A in the triangle below?

Summary:

The measure of angle A in the triangle is 30°.