Answer:
The value of cos Ф is ± 
Step-by-step explanation:
There are important rules for sin Ф and cos Ф
∵ sin Ф = 
∴ sin²Ф = 
∴ sin²Ф = 
→ By using the third rule above
∵ cos²Ф = 1 - sin²Ф
∴ cos²Ф = 1 - 
∴ cos²Ф = 
→ Take square root for both sides
∴ cos Ф = ± 
∴ The value of cos Ф is ± 
Answer:
0.1981
Step-by-step explanation:
See attachment for calculation
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sadly i haven’t learned this so i can’t help you with the answers themselves but a graphing utility you could use is a graphing calculator or a graphing calculator online i know one called desmos.com just not sure if it has the intersect feature so i recommend graphing calculator
I think that would be 9 I am not sure.