Answer:
16. Angle C is approximately 13.0 degrees.
17. The length of segment BC is approximately 45.0.
18. Angle B is approximately 26.0 degrees.
15. The length of segment DF "e" is approximately 12.9.
Step-by-step explanation:
<h3>16</h3>
By the law of sine, the sine of interior angles of a triangle are proportional to the length of the side opposite to that angle.
For triangle ABC:
,- The opposite side of angle A
, - The angle C is to be found, and
- The length of the side opposite to angle C
.
.
.
.
Note that the inverse sine function here
is also known as arcsin.
<h3>17</h3>
By the law of cosine,
,
where
,
, and
are the lengths of sides of triangle ABC, and
is the cosine of angle C.
For triangle ABC:
,
, - The length of
(segment BC) is to be found, and - The cosine of angle A is
.
Therefore, replace C in the equation with A, and the law of cosine will become:
.
.
<h3>18</h3>
For triangle ABC:
,
,
, and- Angle B is to be found.
Start by finding the cosine of angle B. Apply the law of cosine.
.
.
.
<h3>15</h3>
For triangle DEF:
- The length of segment DF is to be found,
- The length of segment EF is 9,
- The sine of angle E is
, and - The sine of angle D is
.
Apply the law of sine:

.
Problem 11
Answer: Angle C and angle F
Explanation: Angle C and the 80 degree angle are vertical angles. Vertical angles are always congruent. Angle F is equal to angle C because they are alternate interior angles.
============================================
Problem 12
Answer: 100 degrees
Explanation: Solve the equation E+F = 180, where F = 80 found earlier above. You should get E = 100.
============================================
Problem 13
Answer: 80 degrees
Explanation: This was mentioned earlier in problem 11.
============================================
Problem 14
Answers: complement = 50, supplement = 140
Explanation: Complementary angles always add to 90. Supplementary angles always add to 180. An example of supplementary angles are angles E and F forming a straight line angle.
Answer:
6√10
Step-by-step explanation:
factorizing 6 and 60
6 = 2 x 3
60 = 2 x 2 x 3 x 5
hence
√6 · √60
= √ [ (2 x 3) · (2 x 2 x 3 x 5) ]
= √ (2· 2² · 3² · 5)
= √ (2² · 3²) x √(2·5)
= (2 · 3) x √10
= 6√10