Mathematics Question and Solution
13² = 20²+11²-2*20*11cosa
169 = 521-440cosa
440cosa = 521-169
cosa = 352/440
a = 36.8698976458°
(13/sin36.8698976458) = (11/sinb)
b = 30.5102374061°
c = 180-a-b
c = 112.6198649481°
d = 90-a
d = 53.1301023542°
e = c-d
e = 59.4897625939°
cos53.1301023542 = f/11
f = 6.6 units.
cos59.4897625939 = g/6.6
g = 3.3507692308 units.
sin59.4897625939 = h/6.6
h = 5.6861538462 units.
Therefore, area red is;
0.5gh
= 0.5*3.3507692308*5.6861538462
= 9.5264946746 square units.
