SOLUTION: If cosA = 8/17 and cosecB = 5/4 and both A and B are acute angles. Calculate the value of cos(A-B) without using a calculator.

Question 1040635: If cosA = 8/17 and cosecB = 5/4 and both A and B are acute angles. Calculate the value of cos(A-B) without using a calculator.
Found 2 solutions by Fombitz, MathTherapy:
Answer by Fombitz(32388) (Show Source): You can put this solution on YOUR website!

Use

to find and .

and

Then use the formula,

Substitute,

Complete that for the final answer.

Answer by MathTherapy(10552) (Show Source): You can put this solution on YOUR website!
If cosA = 8/17 and cosecB = 5/4 and both A and B are acute angles. Calculate the value of cos(A-B) without using a calculator.

;
----- 8-15-17 special right triangle ------ 3-4-5 special right triangle
cos (A - B) = cos A cos B + sin A sin B
cos (A - B) =
cos (A - B) = ------- No cancellation was done since it's easier to obtain final answer with the current denominators

RELATED QUESTIONS
If sin A=3/5, cos B=8/17, and A and B are acute angles, determine the exact value of tan... (answered by MathLover1,Solver92311)
If sin A = 3/5 and cos B = 12/13, and A and B are both positive acute angles, find the... (answered by ikleyn)
Given that A and B are acute angles such that sin A = 3/5 and cos B = 5/13, calculate the (answered by ikleyn)
a and b are positive acute angles. if sin a= 3/5 and cos b= 12/13, find the value of... (answered by lwsshak3)
If A and B are acute angles such that sin(A) = 3/5 and cos(B) = 5/13, find tan(A+B)... (answered by ikleyn)
Given that A and B are acute and Sin A = 4/5, Cos B = 7/25. Find wihout using table the... (answered by lwsshak3)
A and B are positive acute angles. If sinA=4/5 and cosB=8/17, find the value of tan(A-B) (answered by stanbon)
If A and B are both acute angles, tan A = 4/7 and tan B = 8, find the exact value of tan... (answered by ikleyn,Fombitz)
If sin P=12/13 and cos Q=3/5 and both are acute angles,determine without the use of... (answered by lwsshak3)