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Sagot :
Answer:
∠TAC is approximately equal to 61.6°
Step-by-step explanation:
The given parameters for the pyramid are;
The dimension for the rectangular base are; Length = 9 cm, width = 7 cm
The length of the diagonal sides, TA, TB, TC, and TD = 12 cm each
The midpoint of the rectangular base = Point M
The diagonal AC = AM + MC
AM = MC as given M is the midpoint of the rectangular base
∴ AC = AM + MC = 2·AM
By Pythagoras' theorem, AC = √(9² + 7²) = √130
AC = √130 cm
∴ AM = AC/2 = (√130)/2 cm
Alternatively, AM = √((9/2 cm)² + (7/2 cm)²) = √(32.5) cm
∠TAC = ∠TAM
By trigonometric ratios, we have;
[tex]cos (\theta) = \dfrac{Length \ of \ adjacent \ side \ to \ angle }{Length \ of \ hypotenuse\ side \ to \ angle}[/tex]
[tex]\therefore cos (\angle TAM) = cos (\angle TAC) = \dfrac{\left (\dfrac{\sqrt{130} }{2} \right )}{12} = \dfrac{\sqrt{130} }{2 \times 12} = \dfrac{\sqrt{130} }{24}[/tex]
[tex]\angle TAC = arccos \left ( \dfrac{\sqrt{130} }{24} \right ) \approx 61.6 ^{\circ} \ to 1 \ decimal \ place[/tex]
The measure of angle TAC is 61.6 degrees
The given parameters are:
[tex]\mathbf{AB = 7}[/tex]
[tex]\mathbf{BC = 9}[/tex]
Start by calculating length AC, using the following Pythagoras theorem.
[tex]\mathbf{AC = \sqrt{AB^2 + BC^2}}[/tex]
So, we have:
[tex]\mathbf{AC = \sqrt{7^2 + 9^2}}[/tex]
[tex]\mathbf{AC = \sqrt{49 + 81}}[/tex]
[tex]\mathbf{AC = \sqrt{130}}[/tex]
[tex]\mathbf{AC = 11.40}[/tex]
Next, we calculate side length AM
[tex]\mathbf{AM = \frac{AC}{2}}[/tex]
So, we have:
[tex]\mathbf{AM = \frac{11.40}{2}}[/tex]
[tex]\mathbf{AM = 5.70}[/tex]
The measure of angle TAC is calculated using the following cosine ratio
[tex]\mathbf{cos(A)= \frac{AM}{TA}}[/tex]
So, we have:
[tex]\mathbf{cos(A)= \frac{5.70}{12}}[/tex]
[tex]\mathbf{cos(A)= 0.475}[/tex]
Take arc cos of both sides
[tex]\mathbf{A= 61.6}[/tex]
Hence, the measure of angle TAC is 61.6 degrees
Read more about pyramids at:
https://brainly.com/question/15591430
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