How Can You Solve a Triangle Using the Law of Sines Without a Calculator?

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SUMMARY

The discussion focuses on solving Triangle ABC using the Law of Sines without a calculator, given that tan A = 3/4, tan B = 1, and side a = 10. The angle B is determined to be 45 degrees due to tan B = 1. To find sin A from tan A, participants suggest constructing a right triangle with opposite side 3 and adjacent side 4, leading to the calculation of the hypotenuse and subsequently sin A. The calculated value of side b is approximately 11.8 when using a calculator.

PREREQUISITES
  • Understanding of trigonometric functions, specifically tangent and sine.
  • Familiarity with the Law of Sines for solving triangles.
  • Basic knowledge of right triangle properties and Pythagorean theorem.
  • Ability to convert between trigonometric ratios and angle measures.
NEXT STEPS
  • Study the derivation and applications of the Law of Sines in triangle solving.
  • Learn how to calculate sine and cosine from tangent values without a calculator.
  • Explore the relationships between angles and sides in right triangles.
  • Practice solving various triangle problems using trigonometric identities.
USEFUL FOR

Students studying trigonometry, educators teaching triangle properties, and anyone looking to enhance their problem-solving skills in geometry without relying on calculators.

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Homework Statement


In Triangle ABC, tan A=3/4, tan B=1, and a=10. Find what b equals.


Homework Equations


You can use sina/A=sinb/B


The Attempt at a Solution


This problem is really easy using inv tangent functions and what not, but my teacher said we should be able to get it without a calculator.
Doing it with a calculator b will turn out to be 11.8. But if anyone is able to provide a detailed way to get the problem without using a calculator, that would be great.

Thanks
 
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If tanB = 1, what's the measure of angle B? That's an easy one, and one that you should know. Also, if tanA = 3/4, it's pretty easy to get sinA.
 
well the tanB=1 is equal to 45 degrees, but how can you get sinA from tanA?
 
If tanB = 1, then B is 45 degrees - that's what you meant, right?

You have tanA = 3/4. Draw a right triangle and label the side opposite to A as 3 and the side adjacent to A as 4. What does the hypotenuse have to be? From that, what's sinA?
 

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