Applications of the cosine rule
Interactive practice questions
A triangle has sides of length $13$13 cm, $15$15 cm and $5$5 cm. The largest angle has a size of $x$x$^{\circ}$∘. Calculate $x$x.
Round your answer to the nearest degree.
Find the length of the diagonal, $x$x, in parallelogram $ABCD$ABCD.
Round your answer to two decimal places.
A parallelogram has a side of length $13$13 cm and a diagonal of length $58$58 cm. If the angle between these two is $17^\circ$17° and the length of the other side is $x$x cm, find $x$x.
Round your answer to one decimal place.
Mae went for a bike ride on Sunday morning from Point A to Point B , which was $18$18 kilometers long. She then took a $126^\circ$126° turn and rode from Point B to Point C, which was $21$21 kilometers long. How far was she from her starting point?
Round your answer to two decimal places.