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below is a picture of a right triangle abc with right angle c along wit…

Question

below is a picture of a right triangle abc with right angle c along with the point d so that \\(\overline{cd}\\) is perpendicular to \\(\overline{ab}\\).

(image of right triangle abc with right angle at c, cd perpendicular to ab, ad = 5, cd = 12)

a. name all of the triangles that are similar to triangle adc.
\\(\triangle adc \sim \triangle\\) type your answer...
\\(\sim \triangle\\) type your answer...

b. find the lengths of segments \\(\overline{ac}\\), \\(\overline{cb}\\), and \\(\overline{db}\\).
\\(\overline{ac}\\) = type your answer...
\\(\overline{cb}\\) = type your answer...
\\(\overline{db}\\) = type your answer...

Explanation:

Part a

Step1: Recall Similar Triangles in Right Triangles

In a right triangle, when an altitude is drawn to the hypotenuse, the two smaller triangles are similar to the original triangle and to each other. For right triangle \(ABC\) with right angle \(C\) and altitude \(CD\) to hypotenuse \(AB\), we have:

  • \(\triangle ADC\) is a right triangle (right angle at \(D\)).
  • \(\triangle ABC\) is the original right triangle (right angle at \(C\)).
  • \(\triangle CDB\) is the other smaller right triangle (right angle at \(D\)).

To prove similarity, we use AA (Angle - Angle) criterion.

  • For \(\triangle ADC\) and \(\triangle ABC\): \(\angle ADC=\angle ACB = 90^{\circ}\) and \(\angle A\) is common to both triangles. So, by AA, \(\triangle ADC\sim\triangle ABC\).
  • For \(\triangle ADC\) and \(\triangle CDB\): \(\angle ADC=\angle CDB = 90^{\circ}\), and \(\angle ACD=\angle B\) (because \(\angle A+\angle ACD = 90^{\circ}\) and \(\angle A+\angle B=90^{\circ}\), so \(\angle ACD=\angle B\)). So, by AA, \(\triangle ADC\sim\triangle CDB\).

Step1: Find \(AC\)

In right triangle \(ADC\), we know \(AD = 5\) and \(CD=12\). Using the Pythagorean theorem \(AC^{2}=AD^{2}+CD^{2}\) (since \(\triangle ADC\) is a right triangle with legs \(AD\) and \(CD\) and hypotenuse \(AC\)).

$$AC=\sqrt{AD^{2}+CD^{2}}=\sqrt{5^{2}+12^{2}}=\sqrt{25 + 144}=\sqrt{169}=13$$

Step2: Find \(AC\) (Alternative - Using Similar Triangles for \(CB\) and \(DB\))

Since \(\triangle ADC\sim\triangle CDB\), the ratios of corresponding sides are equal. That is, \(\frac{AD}{CD}=\frac{CD}{DB}\) (corresponding sides of similar triangles). We know \(AD = 5\) and \(CD = 12\). Let \(DB=x\). Then \(\frac{5}{12}=\frac{12}{x}\), cross - multiplying gives \(5x=144\), so \(x=\frac{144}{5}=28.8\). But we can also use the similarity between \(\triangle ADC\) and \(\triangle ABC\) to find \(AB\) first.

Since \(\triangle ADC\sim\triangle ABC\), \(\frac{AD}{AC}=\frac{AC}{AB}\). We know \(AD = 5\) and \(AC = 13\). Let \(AB=y\). Then \(\frac{5}{13}=\frac{13}{y}\), cross - multiplying gives \(5y = 169\), so \(y=\frac{169}{5}=33.8\). But \(AB=AD + DB\), so \(DB=AB - AD=33.8 - 5 = 28.8=\frac{144}{5}\).

Now, to find \(CB\), since \(\triangle ADC\sim\triangle CDB\), \(\frac{CD}{CB}=\frac{AD}{CD}\). We know \(CD = 12\) and \(AD = 5\). Let \(CB = z\). Then \(\frac{12}{z}=\frac{5}{12}\), cross - multiplying gives \(5z=144\), so \(z=\frac{144}{5}=28.8\)? Wait, no. Wait, from \(\triangle ABC\), using Pythagorean theorem: \(AB=\frac{AC^{2}}{AD}=\frac{13^{2}}{5}=\frac{169}{5}\), \(CB=\sqrt{AB^{2}-AC^{2}}=\sqrt{(\frac{169}{5})^{2}-13^{2}}=\sqrt{\frac{28561}{25}-\frac{4225}{25}}=\sqrt{\frac{28561 - 4225}{25}}=\sqrt{\frac{24336}{25}}=\frac{156}{5}=31.2\)? Wait, I made a mistake earlier. Let's correct it.

Wait, in right triangle \(ADC\), \(AD = 5\), \(CD = 12\), so \(AC=\sqrt{5^{2}+12^{2}} = 13\) (correct). Since \(\triangle ADC\sim\triangle CDB\), \(\angle A=\angle BCD\) and \(\angle ACD=\angle B\). Also, \(\triangle ABC\sim\triangle ADC\), so \(\frac{AC}{AB}=\frac{AD}{AC}\), so \(AB=\frac{AC^{2}}{AD}=\frac{13^{2}}{5}=\frac{169}{5} = 33.8\). Then \(DB=AB - AD=\frac{169}{5}-5=\frac{169 - 25}{5}=\frac{144}{5}=28.8\). And \(CB\): in \(\triangle ABC\), using Pythagorean theorem \(CB=\sqrt{AB^{2}-AC^{2}}=\sqrt{(\frac{169}{5})^{2}-13^{2}}=\sqrt{\frac{28561}{25}-\frac{4225}{25}}=\sqrt{\frac{24336}{25}}=\frac{156}{5}=31.2\). Wait, another way: since \(\triangle ADC\sim\triangle CDB\), \(\frac{CD}{CB}=\frac{AD}{CD}\), so \(CB=\frac{CD^{2}}{AD}=\frac{12^{2}}{5}=\frac{144}{5}=28.8\)? No, that's wrong. Wait, the correct ratio for similar triangles \(\triangle ADC\) and \(\triangle CDB\) is \(\frac{AD}{CD}=\frac{CD}{DB}=\frac{AC}{CB}\). So \(\frac{AD}{CD}=\frac{5}{12}\), \(\frac{CD}{DB}=\frac{12}{DB}\), so \(\frac{5}{12}=\frac{12}{DB}\) gives \(DB=\frac{144}{5}=28.8\). And \(\frac{AC}{CB}=\frac{5}{12}\), since \(AC = 13\), then \(CB=\frac{12\times13}{5}=\frac{156}{5}=31.2\). Wait, let's use Pythagorean theorem on \(\triangle ABC\). \(AB=AD + DB=5+\frac{144}{5}=\frac{25 + 144}{5}=\frac{169}{5}\). Then \(BC=\sqrt{AB^{2}-AC^{2}}=\sqrt{(\frac{169}{5})^{2}-13^{2}}=\sqrt{\frac{28561 - 4225}{25}}=\sqrt{\frac{24336}{25}}=\frac{156}{5}=31.2\). And \(AC = 13\) (from Pythagorean theorem in \(\triangle ADC\): \(5 - 12-13\) triangle).

Step1 (Correct for \(AC\)):

In right triangle \(ADC\), by Pythagorean theorem:

$$AC=\sqrt{AD^{2}+CD^{2}}=\sqrt{5^{2}+12^{2}}=\sqrt{25 + 144}=\sqrt{169}=13$$

Step2 (For \(CB\)):

Since \(\triangle ADC\sim\triangle CDB\), \(\frac{CD}{CB}=\frac{AD}{CD}\) (corresponding sides). So \(CB=\frac{CD^{2}}{AD}=\frac{12^{2}}{5}=\frac{1…

Answer:

\(\triangle ADC\sim\triangle ABC\) \(\sim\triangle CDB\)

Part b