Solving a Trigonometric Equation: v^2*sin(180-2theta2)/g

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SUMMARY

The discussion centers on solving the trigonometric equation v^2*sin(180-2theta2)/g, derived from substituting theta1 = 90 - theta2 into the equation. Participants emphasize the importance of using trigonometric identities to demonstrate the equality of both sides of the equation. Key identities mentioned include the sum and difference identities, which are crucial for simplifying expressions like sin(180-x) and sin(90-x). The conversation highlights the necessity of understanding these identities to progress in solving the equation.

PREREQUISITES
  • Understanding of trigonometric identities, specifically sum and difference identities
  • Familiarity with the sine function and its properties
  • Basic knowledge of algebraic manipulation in trigonometric equations
  • Ability to interpret and apply mathematical equations in physics contexts
NEXT STEPS
  • Study the list of trigonometric identities available at https://bitly.com/trigiden
  • Practice simplifying expressions using identities like sin(180-x) and sin(90-x)
  • Explore applications of trigonometric equations in physics, particularly in projectile motion
  • Learn about the derivation and application of the sine rule in solving triangles
USEFUL FOR

Students studying trigonometry, physics enthusiasts, and educators looking to enhance their understanding of trigonometric equations and identities.

DeltaForce
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Homework Statement
Show that the range of the projectile is the same for two different projection angles --- a pair that add up to 90 degrees.
Relevant Equations
theta1 +theta2 = 90

v^2 * sin(2theta1)/g = v^2 *sin(2theta2)/g
theta1 = 90- theta2
I substituted that into v^2*sin(2theta1)/g
So I get
v^2*sin(180-2theta2)/g

Now I'm stuck. What do I do next?
 
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You need to go back to the equation. You need to show that the 2 sides of the equation are indeed equal, using some trigonometric identities. You may find this list of identities helpful. https://bitly.com/trigiden
 
Ohh... ok. So it has something to do with the sum and difference identities. Thank you.
 
DeltaForce said:
What do I do next
You ought to know how to simplify sin(180-x), sin(90-x), sin(180+x), and likewise with cos.
 
Yeah. I got it with the trig identities.
 

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