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End of Unit Test on Right Angled Triangles for S3 Students

Score to pass: 70%

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Right-Angled Triangles Unit Summary

 

1. Pythagoras theorem

 

Consider the right-angled triangle ABC shown in figure below:

 

Figure 1

 

Pythagoras theorem states that: \(a^{2}+b^{2}=c^{2}\)

 

2. The median theorem of a right angled triangle states that. The median from the right-angled vertex to the hypotenuse is half the length of the hypotenuse.

Consider the right angled triangle XYZ

 

Figure 2

 

\(WX=\frac{1}{2}YZ\), hence, WX=WZ=WY.

 

3. The altitude theorem of a right angled triangle states that: “The altitude to the hypotenuse of a right-angled triangle is the mean proportional between the segments into which it divides the hypotenuse.”

Consider the right-angled triangle EFG.

 

Figure 3

 

\(\frac{\text{ altitude }}{\text{ part of hypotenuse }}=\frac{\text{ other part of hypotenuse }}{\text{ altitude }}\)

 

\(\frac{HG}{EH}=\frac{HF}{HG}\)

 

4. The leg theorem of a right-angled triangle states that “the leg of a right-angled triangle is the mean proportional between the hypotenuse and the projection of the leg on the hypotenuse.” It can be simply presented as;

 

\(\frac{\text{ leg }}{\text{ hypotenuse }}=\frac{\text{ projection of leg }}{\text{ leg}}\)

 

From Figure 3, we can write: \(\frac{EG}{EF}=\frac{EH}{EG}\) or \(\frac{GF}{EF}=\frac{HF}{GH}\)

 

5. Trigonometric ratios

Consider the Figure 4 below:

Figure 4

 

 

\(\sin \theta =\frac{BC}{AC}\), \(\cos \theta =\frac{AB}{AC}\), \(\tan \theta =\frac{BC}{AB}\).

 

 

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