Question

How do I solve this problem?

Answer 1

Length of required cable is `108.43` feet.

Explanation:

Let us draw a line horizontally from base at `W`, where guy wire is attached and a vertical line from top of tower `T` cutting the hill at `B` and the horizontal line ftom `W` at `P`, as shown below.

Now `m/_BWP=68^@` and therefore we have

`m/_WBP=90^@-68^@=22^@` and

`m/_WBT=180^@-22^@=158^@`

Now in `DeltaWBT`, we have

`BT=29`, `WB=81` and `m/_WBT=158^@`

and using cosine formula

`WT^2=29^2+81^2-2xx29xx81xxcos158^@`

= `841+6561-4698xx(-0.9272)`

= `7402+4356`

= `11758`

and `WT=sqrt3046=108.43` feet.