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High School Archive

Browse High School Trigonometry
Stars indicate particularly interesting answers or good places to begin browsing.

Selected answers to common questions:
    DeMoivre's theorem.
    Volume of a tank.

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Trig Proof - Newton's Formula [04/09/1998]

Can you prove that: (a - b)/c = sin ((1/2)(A - B))/cos ((1/2)(C))?

Trig Proof: Two Methods [03/26/1998]

Prove: (1 + sin x + cos x)/(1 - sin x + cos x) = (1 + sin x)/cos x.

Trig Ratios of a Right Angle in a Right Triangle [09/21/2006]

I'm learning about trig ratios in terms of the hypotenuse, opposite, and adjacent sides of a right triangle. I'm wondering how those sides apply to the right angle? Is the hypotenuse the opposite? What's the adjacent?

Trig Word Problem [5/5/1996]

Find the height of the tower...

Trisected Hypotenuse of a Triangle [12/20/1998]

In right triangle ABC, with C as the right angle... what is the length of AB (the hypotenuse)?

Tutorial material/books/help [11/16/1998]

Can you suggest something I can order or download to help me with trigonometry and pre-calculus?

Two Airplanes [08/28/1997]

Draw a diagram using coordinate system with origin O - how far apart are the airplanes? Express the answer in radical form.

Two Dogs Pulling a Sled [10/15/2001]

What are the magnitude and direction of the force the person will have to exert on the sled to keep it moving along the centerline of the road at constant velocity?

Two Problems on Tangents [07/09/1998]

How can you show that the arc and the angle formed by two tangents are supplementary? Find the radius of circle O, given the following...

Two Triangle Problems [6/11/1996]

One angle of a triangle is trisected... Find the shortest side.

Two Trigonometry Questions [1/22/1995]

What is sin60 * cos60, and tan45 * tan3?

Understanding Bearings in Directional Problems [01/14/2004]

A boat sails 10km from a harbor H on a bearing of S30 degree E. It then sails 15 km on a bearing of N20 degree E. How far is the boat from H? What is the bearing from H?

Unit Sphere [01/21/2002]

Is there such thing as a "unit sphere" that has to do with trigonometric functions and the placement of points on said sphere?

Usefulness of De Moivre's Theorem [2/10/1996]

What is the usefulness of de Moivre's theorem?

Using Forth to Find asin(x) or acos(x) [03/16/2004]

I am writing a program in Forth. I have available tan, atan, cos and sin. I have three sides of an oblique triangle. How can I find the angles? I know I can do it if I have asin. Is there another way, or can I define asin in terms of what I have available?

Using Graphs of Trigonometric Functions [10/9/1995]

We are working on csc, sec, and cot graphs, including how to change the sin, cos, and tan graphs to get them. I am interested in applications of these graphs. In what field would it be useful to know the period, the location of the asymptotes, and the domain of a sec graph?

Using Newton's Method to Solve an Implicit Equation [10/14/2007]

How can I solve the equation (sin(X))/X = 0.7031? My book gives the answer but does not explain how to find it.

Using Phase Shifts to Modify a Sine Curve [06/30/2005]

What modifiers can be used to fatten a sine wave while not affecting the zeros and peaks?

Using Sine and Tangent to Find Pi [08/01/1998]

How can I determine the sine or tangent of an angle without using a calculator?

Using Slopes to Find the Angle between Lines [11/02/2005]

What is the formula to find the acute angle between two intersecting lines?

Using the Law of Cosines [8/18/1995]

Prove that, in any triangle, the sum of the squares of two sides is equal to twice the square on half the third side plus twice the square on the line joining the midpoint of the third side to its opposite vertex.

Using the Law of Cosines [05/21/1998]

Given the length of three sides of a triangle, how can I find the angle between any two of the sides?

Using the Laws of Sine and Cosine [9/24/1995]

How do I find the sine and cosine of pi/12?

Using Trig Identities to Simplify [7/26/1996]

How do I simplify ((sin @ - 1)/cos @) - (cos @/(sin @ -1)) ?

Using Trigonometric Identities [05/31/1999]

How can I prove that sin(4x) = 2sin(2x) - 8sin^3(x)cosx ?

Value of Angle DBC [1/23/1996]

Imagine a triangle ABC on which angles B and C are equal to 80...

Vector Angles: Prove A.B = |A||B|cosA [07/13/1998]

I just finished my pre-calc class, and at the end we covered vectors...

Verifying Trigonometric Identities [07/12/2002]

How do you verify a trigonometric identity?

Verify the Identity [04/17/2003]

Verify the identity: (csc x)/(tan x + cot x) = cos x.

Vertices of an Octagon [10/29/1996]

Find the coordinates of the vertices of an octagon with center (0,0) when it is inscribed in a square.

What Is the Length of PR? [01/01/2003]

In a circle of radius 6, a triangle PQR is drawn having QR=8 and PQ=10.

What is the Longest Pole? [04/04/1999]

A metal pole L ft long is pushed on the floor from one corridor into another corridor at a right angle...

What is the Relation between tan and tanh? [08/25/2001]

I want to know the relation between tangent and hyperbolic tangent.

What is Trigonometry? [8/20/1996]

What is trigonometry, and what is it used for?

What's 'Arccos'? [06/17/2001]

I'm trying to write a program in Visual Basic 6 about the distance calculation between two cities.

When to Use Law of Sines or Law of Cosines [02/01/2006]

When do we use the law of sines as opposed to the law of cosines?

Where Will the Runners Meet? [03/29/1999]

Two runners, A and B, start 90 degrees away from each other on a circular track and run at the same speed. If Runner B decides to cut across the track, where will they meet?

Which Side is Longer? [1/27/1995]

You are given a quadrilateral, ABCD, with diagonal DB, angle ADC = 90, angle DBC = 43, angle C = 91, side AD = 9, side DC = 9. Find which is longer AB or AD.

Why does a/SinA = b/SinB = c/SinC? [08/12/1997]

I was just playing aroung with a proof of a triangle and came across the fact that a/SinA = b/SinB = c/SinC. Why?

Why Radians? [12/03/1997]

Why use radians to measure angles over degrees?

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