Help Solving Trig Equation: Cos70°cos20°-sin70°sin20°

  • Thread starter CrossFit415
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In summary, a trigonometric equation is an equation involving trigonometric functions used to solve for unknown angles or values in a right triangle. The process for solving these equations involves using trigonometric identities and inverse trigonometric functions. The main difference between solving a trigonometric equation and a regular algebraic equation is the use of trigonometric functions. The purpose of solving a trigonometric equation is to find unknown values in a right triangle or real-life problems involving trigonometry. Solutions can be checked by plugging them back into the equation or using a calculator to graph the equation.
  • #1
CrossFit415
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Cos70°cos20°-sin70°sin20°

I can't find any of these angles that are equivalent to the basic angles. Thanks
 
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  • #2
Do you know a formula for cos(a+b) in terms of the trig functions evaluated at a and b?
 
  • #3
Cost(a+b)=cos a • cos b - sin a • sin b
 
  • #4
I don't know which angles are equivalent to 70° nor 20°
 
  • #5
But you know cos(20+70)=cos(90), right?
 
  • #6
Whoops. Thanks
 

What is a trigonometric equation?

A trigonometric equation is an equation that involves trigonometric functions, such as sine, cosine, and tangent. These equations are typically used to solve for unknown angles or values in a right triangle.

What is the process for solving a trigonometric equation?

The process for solving a trigonometric equation involves using trigonometric identities, such as the Pythagorean identity and the double angle identity, to simplify the equation and then using inverse trigonometric functions to find the solutions.

What is the difference between solving a trigonometric equation and solving a regular algebraic equation?

The main difference between solving a trigonometric equation and solving a regular algebraic equation is that trigonometric equations involve trigonometric functions, which have specific properties and identities that must be used in the solving process. Algebraic equations, on the other hand, only involve basic arithmetic operations.

What is the purpose of solving a trigonometric equation?

The purpose of solving a trigonometric equation is to find the values of unknown angles or sides in a right triangle, or to find solutions for real-life problems that involve trigonometry, such as determining the height of a building or the distance between two points.

How do I know if my solution to a trigonometric equation is correct?

You can check the validity of your solution by plugging it back into the original equation and seeing if it satisfies the equation. Additionally, you can use a calculator to graph the equation and visually confirm that your solution is correct.

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