Using tangents in Solving Triangles

if you know the tangent ratio of a given angle, you already know that the ratio is a result of dividing opposite side over tangent. If you know the length of one side, the you can get the other.

let us say there exits an angle θ that has a tan ratio of 0.821 and the side opposite to it is 8.5 cm. Then the adjacent side can be obtained as follow:

Example

Find the length BC in the figure below:

solution

The side BC is the opposite side and line AB which is the adjacent side to angle  θ which is equal to  70o is equal to 25cm. Then we proceeds as follows:

Exercise Questions

Use tangents to find the lengths of the side marked x in the below tri-angles.

Q1: Find the unknown side in each of the following

(a)

(b)

Q2: Find the unknown angle θ,α in each of the following triangle

(a)

(b)

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