Answer:
m∠BAD = 88.83°
Step-by-step explanation:
By drawing a diagonal BD, we get a triangle ABD from the given rectangle pyramid.
Length of the diagonal BD (diagonal of rectangle BCDE) = [tex]\sqrt{\text{Length}^{2}+\text{Width}^2 }[/tex]
= [tex]\sqrt{12^{2}+16^{2}}[/tex]
= [tex]\sqrt{400}[/tex]
= 20 cm
By applying cosine rule in ΔABD,
BD² = AB² + AD²- 2(AB)(AD)cos(∠BAD)
20² = 14² + 14² - 2(14)(14)cos(∠BAD)
400 = 196 + 196 - 392cos(∠BAD)
400 - 392 = 392cos(∠BAD)
cos(∠BAD) = [tex]\frac{8}{392}[/tex]
m(∠BAD) = [tex]\text{cos}^{-1}(\frac{8}{392})[/tex]
= 88.83°
