Two points A and B lie on opposite sides of a river. Another point C is located on the same side of the river as B at a distance of 240 ft from B. If angle ABC is 100° and angle ACB is 25°, find the distance across the river from A to B. (Round your answer to two decimal places.)

Respuesta :

Answer:

128.98 feet

Step-by-step explanation:

By the given information,

Suppose ABC is a triangle,

According to the question,

BC = 240 feet,

m∠ABC = 100°,

m∠ACB = 25°,

∵ m∠ACB + m∠ABC + m∠BAC = 180°,

25° + 100° + m∠BAC = 180°,

125° + m∠BAC = 180°,

⇒ m∠BAC = 55°,

Now the law of sine,

[tex]\frac{\sin C}{AB}=\frac{\sin A}{BC}[/tex]

[tex]\frac{\sin 25^{\circ}}{AB}=\frac{\sin 55^{\circ}}{240}[/tex]

[tex]\implies AB = \frac{250 \sin 25^{\circ}}{\sin 55^{\circ}}\approx 128.98[/tex]

Hence, the distance between A and B would be 128.98 ft ( approx )

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