Question

What is the area of this triangle? B O 15.75 sq. units O 31.5 sq. units O . 13.2 sq. units O 1937.25 sq. units 7 123° С 4.5

Answer 1

Area = B x H/2

B= 4.5

AB^2 = 4.5^2 + 7^2 - 4.5•7•cos 123 ( this is Cosin theorem)

Now find height

External angle = 180° - 123°= 57°

Then

Sin 57° = H/7

H= 7• Sin 57°= 5.87

Then now find area BxH/2

Triangle area= 4.5 x 5.87/2= 13.207

Then answer is OPTION C) 13.2 square units