Fermi · Concept Library · Courses · Books · Problems · Simulations · Math Wiki · High School Fermi › Problems In a quadrilateral
MATHEMATICS · Single correct · CBSE · Mathematics · Vector Algebra · Vector Algebra
Problem In a quadrilateral A B C D ABCD A B C D A C AC A C ∠ ( A B , A D ) \angle (AB, AD) ∠ ( A B , A D ) 2 π 3 \frac{2\pi}{3} 3 2 π 15 ∣ A C ∣ = 3 ∣ A B ∣ = 5 ∣ A D ∣ 15|\mathbf{AC}| = 3|\mathbf{AB}| = 5|\mathbf{AD}| 15∣ AC ∣ = 3∣ AB ∣ = 5∣ AD ∣ cos ( B A , C D ) \cos(\mathbf{BA}, \mathbf{CD}) cos ( BA , CD ) − 14 7 2 -\frac{\sqrt{14}}{7\sqrt{2}} − 7 2 14 − 21 7 3 -\frac{\sqrt{21}}{7\sqrt{3}} − 7 3 21 2 7 \frac{2}{\sqrt{7}} 7 2 2 7 14 \frac{2\sqrt{7}}{14} 14 2 7 Browse the problem library