Respuesta :

[tex]\\ \sf\longmapsto CD^2=AD\times DB[/tex]

[tex]\\ \sf\longmapsto 12^2=16DB[/tex]

[tex]\\ \sf\longmapsto 144=16DB[/tex]

[tex]\\ \sf\longmapsto DB=\dfrac{144}{16}[/tex]

[tex]\\ \sf\longmapsto DB=8[/tex]

Answer:

• let's first consinder triangle ADC

• from trigonometric ratios:

[tex] \hookrightarrow \: { \rm{ \tan( \theta) = \frac{opposite}{adjacent} }} \\ [/tex]

→ theta is the angle CAD

→ opposite is 16

→ adjacent is 12

[tex]{ \tt{ \tan( \theta) = \frac{16}{12} }} \\ \\ { \tt{ \theta = { \tan }^{ - 1}( \frac{16}{12} ) }} \\ \\ { \underline{ \tt{ \: \: \theta = 53.1 \degree \: }}}[/tex]

Then let's find the angle BCD

[tex]{ \tt{ \angle BCD + \angle CAD = 90 \degree}} \\ { \tt{\angle BCD + 53.1 \degree = 90 \degree}} \\ { \underline{ \tt{ \: \: \angle BCD = 36.9 \degree \: \: }}}[/tex]

• from trigonometric ratios:

[tex]{ \rm{ \tan( \theta) = \frac{opposite}{adjacent} }} \\ [/tex]

→ theta is 36.9°

→ opposite is DB

→ adjacent is 12

[tex]{ \tt{ \tan(36.9) = \frac{DB}{12} }} \\ \\ { \tt{DB = 12 \times \tan(36.9) }} \\ \\ { \tt{DB = 12 \times 0.75}} \\ \\ { \rm{answer : \: { \boxed{ \rm{ \: \: DB = 9 \: \: }}}}}[/tex]

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