Question

Find all the missing elements:

B
a
A = 40°
a = 8
b = 7
A
C
b
B = [?]° C = [ ]° c =
C=[ ]
Round to the nearest tenth.
Enter

Answer 1

C=105.8 degrees. c=12

Explanation:

Answer 2

B = 34.2°

C = 58.2° or 121.8°

c= 10.6

Explanation:

Step 1

Finding c

We calculate c using Pythagoras Theorem

c²= a² + b²

c = √a² + b²

a= 8, b = 7

c = √8² + 7²

c = √64 + 49

c = √(113)

c = 10.630145813

Approximately c = 10.6

Step 2

Find B

We solve this using Sine rule

a/sin A = b/sin B

A = 40°

a = 8

b = 7

Hence,

8/sin 40° = 7/sin B

8 × sin B = sin 40° × 7

sin B = sin 40° × 7/8

B = arc sin (sin 40° × 7/8)

B ≈34.22465°

Approximately = 34.2°

Step 3

We find C

Find B

We solve this using Sine rule

b/sin B = c/sin C

B = 34.2°

b = 7

c = 10.6

C = ?

Hence,

7/sin 34.2° = 10.6/sin C

7 × sin C = sin 34.2 × 10.6

sin C = sin 34.2° × 10.6/7

C = arc sin (sin 34.2° × 10.6/7)

C = arcsin(0.85)

C= 58.211669383

Approximately C = 58.2°

Or = 180 - 58.2

C = 121.8°