1 + tan ² Ф=sec²Ф
1+(12/5)²=sec²Ф
169/25=sec² Ф
sec Ф=⁺₋√(169/25)=⁺₋13/5
sec Ф=1/cos Ф ⇒cosФ=1/sec Ф
cos Ф>0 ⇔ sec Ф>0 ⇔ sec Ф=+ 13/5
cos Ф=1/secФ
cos Ф=1 / 13/5=5/13
we can calculate the sin Ф, with this method.
sin²Ф + cos²Ф=1 ⇒ sin Ф=⁺₋√(1-cos² Ф)
sin Ф=⁺₋√[1-(5/13)²]=⁺₋12/13
like cos Ф>0 and tan Ф>0 ⇒ sin Ф>0 ⇒sin Ф=12/13
answer: d.12/13
other method
tan Ф=sin Ф / cos Ф
12/5=sin Ф / 5/13
sin Ф=(12/5)*(5/13)=12/13
answer: d.12/13
Solve your system of equations.
2x+y=1;4x+2y=−1
Solve 2x+y=1 for y:
2x+y+−2x=1+−2x(Add -2x to both sides)
y=−2x+1
Substitute (−2x+1) for y in 4x+2y=−1:
4x+2y=−1
4x+2(−2x+1)=−1
2=−1(Simplify both sides of the equation)
2+−2=−1+−2(Add -2 to both sides)
0=−3
Answer: No solution. C)
This is the concept of trigonometry, we are required to calculate the number of floors the building has given the information above;
# floors=[height of the building]/[height of each floor]
height of each floor=17 ft
let the height of the building be,h.
h is given by;
tan theta=opposite/adjacent
theta=80
opposite=h
adjacent=75 ft
thus
tan 80=h/75
h=75 tan 80
h=425.35 ft
thus the number of floors will be:
425.35/17
=25.020≈25 floors
Step-by-step explanation:
Answer: We should add the constant 81 to the expression to have a perfect square trinomial.
The perfect square trinomial that would be formed would result from (x + 9)^2.
We can use foil to prove it.
(x + 9)(x + 9)
x^2 + 9x + 9x + 81
x^2 + 18x + 81
81 is the value that must go with 18x in the middle to form the perfect square trinomial.
