the diagram shows a 7cm x 6cm rectangle-based pyramid

all the diagonal sides - TA, TB, TC, TD are the length 10 cm

M is the midpoint of the rectangular based.

work out the hight MT. give your answer to 1 decimal place
show your working out

the diagram shows a 7cm x 6cm rectanglebased pyramidall the diagonal sides TA TB TC TD are the length 10 cm M is the midpoint of the rectangular based work out class=

Respuesta :

Answer:

MT = 8.9 cm

Step-by-step explanation:

In the rectangle ABCD, Angle ABC = 90 degree

In the triangle ABC, Angle B = 90 degree

=> ABC is the right angle triangle

According to the Pythagoras theorem, we have the following equation:

+) [tex]AB^{2} + BC^{2} = AC^{2}[/tex]

⇔[tex]6^{2} + 7^{2} = AC^{2}[/tex]

⇔[tex]AC^{2} = 36 + 49 = 85[/tex]

⇔ [tex]AC = \sqrt{85}[/tex] cm

In the rectangle ABCD, M is the midpoint, so that it is also the midpoint of line segment AC.

=> AM = [tex]\frac{AC}{2}=\frac{\sqrt{85} }{2}[/tex] cm

TM is the height of the pyramid, so that it is perpendicular to the base ABCD.

As AM belongs to the surface of the rectangle ABCD

=> TM is also perpendicular to AM

=> AMT is the right-angled triangle with Angle AMT = 90 degree

According the Pythagoras theorem, we have the following equation:

[tex]AM^{2} + MT^{2} = AT^{2}[/tex]

⇔ [tex]MT^{2} = AT^{2} - AM^{2} = 10^{2} - (\frac{\sqrt{85} }{2} )^{2}[/tex]

⇔[tex]MT^{2} = 100 - \frac{85}{4} = \frac{315}{4}[/tex]

⇔[tex]MT = \sqrt{\frac{315}{4} } =\frac{3\sqrt{35} }{2}[/tex] ≈ 8.9 cm

MT = 8.9 cm