Question

Q10.
ABC is a right-angled triangle.
А
11 cm
B
7 cm
C
(a) Work out the size of angle ABC.
Give your answer correct to 1 decimal place.

Answer 1

Answer:

$B = 50.5^\circ$

Step-by-step explanation:

Given

$AB = 11$

$BC = 7$

See attachment

Required

Determine $\angle ABC$

$\angle ABC$ implies that we calculate the angle at B.

Given that:

$AB = 11$ --- Hypotenuse

$BC = 7$ --- Adjacent of B

We apply cosine formula

$\cos(B) = \frac{Adjacent}{Hypotenuse}$

$\cos(B) = \frac{BC}{AB}$

$\cos(B) = \frac{7}{11}$

$\cos(B) = 0.6364$

Take arccos of both sides

$B = cos^{-1}(0.6364)$

$B = 50.5^\circ$